前言

這篇文章緊接上一篇, runtime理論我想大家都知道的, 上一篇是站在個人理解的角度, 探討了相關(guān)的一些動態(tài)原理,和基本實(shí)現(xiàn)思路,最后拓展到runtime框架, 而且也簡單寫了動態(tài)添加屬性和KVO簡單實(shí)現(xiàn)的demo,如果有興趣可以去看深入理解OC的運(yùn)行時(Runtime)

編碼相關(guān)

具體可通過編譯指令 @encode(type) typeof()

@encode(type) 必須傳入類型不能是具體的變量
typeof() 傳入的可以是變量, 可以是類型, 通過typeof獲取到類型然后傳給@encode,最后會返回對應(yīng)的 const char*, 這個就是類型的編碼, 同樣可以獲取到block和函數(shù)的(相當(dāng)于沒有獲取到), 這里舉出一些例子:

** 先定義一個Log輸出的宏(來自RAC宏的運(yùn)用改編,有時間會專門寫一篇宏相關(guān)的東西) ,這里設(shè)置的最多10個參數(shù), 如果不夠,可以自己看著往后加 **


static inline NSString* _LOG_GET_FORMAT(const char* typeCode,size_t size){
    NSString* result;
    ///無符號
    if (strcmp(typeCode, "I") == 0) result = @"%u";

    else if (strcmp(typeCode, "Q") == 0) result = @"%lu";

    else if (strcmp(typeCode, "C") == 0) result = @"%d";

    else if (strcmp(typeCode, "S") == 0) result = @"%d";

    else if (strcmp(typeCode, "i") == 0) {
        /// 可能是 'a' 也可能是 10
        if (size == sizeof(char)) {
            result = @"%c";

        }else result = @"%d";

    }else if(strcmp(typeCode, "q") == 0){
        result = @"%ld";

    }else if(strcmp(typeCode, "c") == 0){
        result = @"%c";

    }else if(strcmp(typeCode, "s") == 0){
        result = @"%d";

    }else if(strcmp(typeCode, "*") == 0){
        /// char*
        result = @"%s";

    }else if(strcmp(typeCode, "f") == 0){
        result = @"%f";

    }else if(strcmp(typeCode, "d") == 0){
        result = @"%f";

    }else{
        NSString* tmp = [NSString stringWithFormat:@"%s",typeCode];
        if ([tmp hasSuffix:@"c]"] || [tmp hasSuffix:@"C]"]) {
            result = @"%s";

        }else if([tmp hasPrefix:@"^"]){ ///指針
            result = @"%p";

        }else if([tmp isEqualToString:@"@"]) {
            result = @"%@";
        }else {
            result = [NSString stringWithFormat:@"%%%s",typeCode];
        }
    }
    return result;
}

#if __OBJC__

#define getTypeStr(_V) {\
NSString* _LogFormatStr = _LOG_GET_FORMAT(@encode(__typeof(_V)),sizeof(_V));\
NSLog(@"after: %@",_LogFormatStr);\
if([_LogFormatStr isEqualToString:@"%@"]) {\
NSLog(@"對象的打印 %@",_LogFormatStr);\
NSLog(_LogFormatStr,_V);\
}\
else {\
printf(_LogFormatStr.UTF8String,_V);\
printf("\n");\
}\
}
#define LogMaxArg 10
#define LogArgList0 10,9,8,7,6,5,4,3,2,1

#define Log(...) Log_args(LogMaxArg,__VA_ARGS__,LogArgList0)(__VA_ARGS__)
#define Log_args(N,...) Log_Find_index(__VA_ARGS__,LogArgList0)
#define Log_Find_index(_0,_1,_2,_3,_4,_5,_6,_7,_8,_9,...) LogFun(Log_,__VA_ARGS__)
#define LogFun(Fun,F,...) Fun##F

#define Log_1(_V)                   getTypeStr(_V)

#define Log_2(_V,...)               getTypeStr(_V);Log_1(__VA_ARGS__)

#define Log_3(_V,...)               getTypeStr(_V);Log_2(__VA_ARGS__)

#define Log_4(_V,...)               getTypeStr(_V);Log_3(__VA_ARGS__)

#define Log_5(_V,...)               getTypeStr(_V);Log_4(__VA_ARGS__)

#define Log_6(_V,...)               getTypeStr(_V);Log_5(__VA_ARGS__)

#define Log_7(_V,...)               getTypeStr(_V);Log_6(__VA_ARGS__)

#define Log_8(_V,...)               getTypeStr(_V);Log_7(__VA_ARGS__)

#define Log_9(_V,...)               getTypeStr(_V);Log_8(__VA_ARGS__)

#define Log_10(_V,...)              getTypeStr(_V);Log_9(__VA_ARGS__)
#endif

使用

////打印整型浮點(diǎn),基本指針
int a = 100;
float b = 1.23432e3;
char ch = 'A';
Log(a,b, 'a', ch, 919123L);

//// 打印結(jié)果
100
1234.319946
97
A
919123

////打印指針
float* fp = &b;
Log(fp, *fp, &b);

///打印結(jié)果
0x7ffee56ce8e8
1234.319946
0x7ffee56ce8e8

///打印c字符串
char *s = "ssssss";
char array[] = "array";
Log("aaa","bbb","ccc", s, array, 123, 890);

///打印結(jié)果:
aaa
bbb
ccc
ssssss
array
123
890


///打印oc對象 如果直接在宏的參數(shù)里填寫字典,數(shù)組, 加上括號,整體括起來
NSArray* tmp = @[@"xxxx",@"bbbb",@{@"array":@123}];
    Log(@"123",
        (@{@"1233":@123}),
        tmp,
        "這個是c的字符串",
        324.12331f
        );

///打印結(jié)果:
{
    1233 = 123;
}
(
    xxxx,
    bbbb,
        {
        array = 123;
    }
)
這個是c的字符串
324.123322

各種數(shù)字(整型,浮點(diǎn))編碼

char: c
short: s
int: i
long: q
NSInteger: q
long long: q
float: f
double: d
unsigned char: C
unsigned short: S
unsigned int: I
unsigned long: Q
NSUInteger: Q
unsigned long long: Q

各種指針的編碼就是在對應(yīng)的類型前面加上^

char* : *
short*: ^s
int*: ^i
long*: ^q
NSInteger*: ^q
long long*: ^q
float*: ^f
double*: ^d
unsigned char*: *
unsigned short*: ^S
unsigned int*: ^I
unsigned long*: ^Q
NSUInteger*: ^Q
unsigned long long*: ^Q
int**: ^^i
void* ^V
void** ^^V

c語言里數(shù)組的編碼

short[]: ^s
int[10]: [10i]
long[5]: [5q]
long long[8]: [9q]
NSInteger[7]: [7q]
unsigned short[]: ^S
....///規(guī)律自己尋找

const相關(guān)的編碼

const int a;     i
int const b;     i
int* const c;    ^i
int const* d;   r^i
const int* e;   r^i

const int a[] = {3};    [1i]
const int b[2];           [2i]
const int* c[] = {  NULL  };    [1^i]
int* const d[2] = {  NULL,NULL }; [2^i]

函數(shù)指針和block相關(guān) ?代表著匿名

   ////局部的函數(shù)指針和block
    void (*funtest)(void) = NULL;  ^?
    void (^blocktest)(void) = NULL; @?
    int (*funtest1)(int) = NULL; ^?
    int (^blocktest1)(int) = NULL;@?

結(jié)構(gòu)體,聯(lián)合體相關(guān)

///系統(tǒng)的
@encode(typeof(CGRect)) {CGRect={CGPoint=dd}{CGSize=dd}}

///自己定義的
struct tmp{
        int a;
        struct{
            int b;
            NSString* c;
        };
    };
///編碼格式結(jié)果
{tmp=i{?=i@}}


///聯(lián)合體
union{
        int a;
        int b;
    }d;
////d的編碼是 ?代表匿名 d這里是一個變量
(?=ii) 

union tmpU{
        int a;
        int b;
    }d;
////此時d的編碼是
(tmpU=ii)

oc相關(guān)的編碼

@encode(typeof(instance))  @
@encode(typeof(NSObject)) {NSObject=#}
@encode(typeof(UIViewController)) {UIViewController=#}

@interface Person :NSObject{
  int* age;
  NSString* name;
}
@end
@encode(typeof(Person)) {UIViewController=#}


////類里方法的編碼通過runtime函數(shù)獲取到method, 然后再獲取編碼

方法簽名

?1. 在NSObject里有一個簽名的類NSMethodSignature
?2. 獲取NSMethodSignature的途徑有
??2.1 通過NSObject的接口

例子如下:


@implementation VC :UIViewController
+ (void)classMT{}
- (void)objcMT{}
@end
/**
-[NSObject methodSignatureForSelector:SEL]這個方法在頭文件里聲明的是對象方法, 但是以類方法的調(diào)用形式去調(diào)用也可以, 不知道為什么
*/

///1  class 獲取 object 方法
NSMethodSignature* obj = [ViewController methodSignatureForSelector:@selector(signatest1)];
    NSLog(@"class get -: %p",obj);

///2 object 獲取 object
    obj = nil;
    obj = [self methodSignatureForSelector:@selector(signatest1)];
    NSLog(@"object get -: %p",obj);

////3 class 獲取 class
    obj = nil;
    obj = [ViewController methodSignatureForSelector:@selector(signatest2)];
    NSLog(@"class get +: %p",obj);

////4 object 獲取 class
    obj = nil;
    obj = [self methodSignatureForSelector:@selector(signatest2)];
    NSLog(@"objcet get +: %p",obj);

////5 class 獲取 object 方式2
    obj = nil;
    obj = [ViewController instanceMethodSignatureForSelector:@selector(signatest1)];
    NSLog(@"class get -: %p",obj);

////5 class 獲取 class  方式2
obj = nil;
    obj = [ViewController instanceMethodSignatureForSelector:@selector(signatest2)];
    NSLog(@"class get +: %p",obj);

日志
0x0
0x600000228b00
0x600000228b00
0x0
0x600000228b00
0x0

總結(jié): 1.如果是獲取對象方法的簽名, 就用對象去調(diào)用methodSignatureForSelector或者用類去調(diào)用instanceMethodSignatureForSelector
???2.如果是獲取類方法的簽名, 就用類去調(diào)用methodSignatureForSelector
?
獲取簽名對象后, 函數(shù)簽名代碼如下:


- (void)signatest3:(int)a arg2:(NSString*)b{
//    return 1;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    NSMethodSignature* obj = [self methodSignatureForSelector:@selector(signatest3:arg2:)];
    for (NSInteger i = 0; i < obj.numberOfArguments; ++i) {
        NSLog(@"%s",[obj getArgumentTypeAtIndex:i]);
    }
    NSLog(@"%s",obj.methodReturnType);
}
////@ : i @ V 
////對應(yīng) IMP的調(diào)用參數(shù)表
//// 第0個 id  @
//// 第1個SEL 對應(yīng) :
//// 第2個開始是參數(shù) 上面的是 int 所以是 i
//// 第3個 對應(yīng)上面的 NSString*  @
//// 返回值要單獨(dú)獲取, 這里是void 所以是V

??2.2 通過runtime的接口

還是上面的那個類定義

Method m = class_getInstanceMethod(ViewController.class, @selector(signatest3:arg2:));
    NSLog(@"%s",method_getTypeEncoding(m));
/// i28@0:8i16@20  這些數(shù)字代表什么含義,沒懂, 但是去掉數(shù)字就和上面對應(yīng)了,而且最開始的是從返回算的

?3. 自己簽名

創(chuàng)建簽名對象 NSMethodSignature 的時候,給的簽名類型,注意創(chuàng)建簽名的時候, 要把返回值也帶上

    NSMethodSignature* method = [NSMethodSignature signatureWithObjCTypes:"i@:i@"];
    for (NSInteger i = 0; i < method.numberOfArguments; ++i) {
        NSLog(@"%s",[method getArgumentTypeAtIndex:i]);
    }
    NSLog(@"%s",method.methodReturnType);
/// @:i@  對應(yīng)的方法  - (int)name:(int)a arg:(id)obj;
/// 第一是返回值 所以創(chuàng)建的時候要指定返回值i

消息轉(zhuǎn)發(fā)(利用系統(tǒng)提供的接口轉(zhuǎn)發(fā))

?在oc里如果對對象發(fā)送消息時, 最后沒有找到方法的實(shí)現(xiàn), 系統(tǒng)會自動進(jìn)入消息轉(zhuǎn)發(fā)流程, 而且在oc的層面提供了接口,在這些接口里我們可以轉(zhuǎn)發(fā)消息, 這里拿對象方法來說

? 1. 進(jìn)入+(bool)resolveInstanceMethod:(SEL)

這里系統(tǒng)會將之前傳入的SEL傳遞過來,我們知道, SEL是oc接收消息后去尋找方法匹配的標(biāo)識,和IMP是分開的, 這里把SEL方法的標(biāo)識傳過來, 表示當(dāng)前類沒有與SEL對應(yīng)的實(shí)現(xiàn)IMP, 所以這里就為這個SEL指定一個實(shí)現(xiàn)地址, 然后返回YES告訴系統(tǒng)處理了, 系統(tǒng)就不會往下走了

@implementation VC : UIViewController
- (void)forwardTestFun1{}

- (void)viewDidLoad{
  [super viewDidLoad];

  ////這里瞎調(diào)用了一個方法, 寫成這樣是為了消除警告
  objc_msgSend(self, sel_registerName("noMethodTest"));
}

+ (BOOL)resolveInstanceMethod:(SEL)sel{
   if (sel_isEqual(sel, sel_getUid("noMethodTest"))) {
        class_addMethod(self, sel, imp_implementationWithBlock(^(id obj){
            Log("已經(jīng)被改變指向了,來到了這里執(zhí)行");
        }), "v@:");


        return 1;
    }
    return [super resolveInstanceMethod:sel];
}

@end

這一步主要的用途是在本類中動態(tài)為sel添加一個Method, 如果這里返回false, 或什么都不管, 就會去下一步. 這里要說明一點(diǎn), 就算將當(dāng)前沒有實(shí)現(xiàn)的noMethodTest的sel 改為forwardTestFun1的sel傳給父類,還是會崩潰

? 2. 消息轉(zhuǎn)發(fā)的第2步:- (id)forwardingTargetForSelector:(SEL)aSelector

這一步要求給系統(tǒng)傳一個對象, 要求這個對象有sel的實(shí)現(xiàn), 比如傳一個Person對象, 他實(shí)現(xiàn)了這sel

?3. 如果2不處理, 即返回了nil,或者沒有實(shí)現(xiàn)會進(jìn)入到這里- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector, 這個方法要求對sel提供一個簽名對象 eg:

- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector{
    return [NSMethodSignature signatureWithObjCTypes:"V@:"];
}

這里的簽名一定要和傳入的sel對應(yīng), 這里表示 - (void)funName{ }, v==void, @ == id : == sel 因?yàn)?objc_msgsend()的參數(shù)是 id, sel, 所以這里要提供@和:

?4. 如果3不實(shí)現(xiàn)或者,返回nil,崩潰, 如果返回了簽名則會執(zhí)行: - (void)forwardInvocation:(NSInvocation *)anInvocation, 這個方法會傳遞一個NSInvocation對象, 簽名已經(jīng)設(shè)置好了, 就是上面的一步我們設(shè)置的簽名, 這個方法要求提供一個對象供anInvocation調(diào)用, 而且要求對象必須實(shí)現(xiàn)了同名的sel的實(shí)現(xiàn)，因?yàn)檫@里的anInvocation的selector系統(tǒng)賦值的是傳過來的sel，所以一定會調(diào)用新對象同名的方法，如果想指定新對象別的方法，這里需要更改anInvocation的selector屬性值，但是對應(yīng)實(shí)現(xiàn)的方法簽名必須和當(dāng)前參數(shù)sel的一致。代碼如下

@implementation Son :NSObject
- (void)test{
  Log("消息會不會被轉(zhuǎn)發(fā)來呢?");
}

- (void)noMethodTest{
  Log("消息一定會轉(zhuǎn)發(fā)到這里");
}
@end


VC中:
- (void)forwardInvocation:(NSInvocation *)anInvocation{
///如果上一步提供的簽名不對, 也是崩潰的
    [anInvocation invokeWithTarget:Son.new];


///這里可以獲取到參數(shù)信息
NSMethodSignature* si = anInvocation.methodSignature;
    for (NSInteger i = 2; i < si.numberOfArguments; ++i) {
        @autoreleasepool {
            __autoreleasing NSObject* s;
            [anInvocation getArgument:&s atIndex:i];
            NSLog(@"%@",s);
        }
    }
}
///如果不實(shí)現(xiàn)noMethodTest, 崩潰, 方法找不到,如果實(shí)現(xiàn)了會調(diào)用noMethodTest

手動觸發(fā)消息轉(zhuǎn)發(fā)(方法監(jiān)聽AOP編程)

? 1. 手動觸發(fā)消息轉(zhuǎn)發(fā)還是和原理一樣的, 要實(shí)現(xiàn)即使當(dāng)前調(diào)用的sel有對應(yīng)的IMP, 也要觸發(fā)轉(zhuǎn)發(fā)流程. 這里要說一點(diǎn)就是, 處理的操作肯定是在轉(zhuǎn)發(fā)流程的其中一步, 因?yàn)榧热皇寝D(zhuǎn)發(fā), 一定會走到轉(zhuǎn)發(fā)流程的函數(shù),所以我們處理的地方就是在那幾步當(dāng)中(針對當(dāng)前類來說,后面拓展到通用的時候?qū)崿F(xiàn)方案又不一樣的)

場景1 假設(shè)現(xiàn)在的需求是項目里所有Person對象用到的地方, 只要調(diào)用了`- [Person runFrom: to:]` 都必須在調(diào)用前打印 `hello world`

解決方案選擇

方案1

找到工程里所有的Person實(shí)例化的對象, 然后查找哪里調(diào)用了- [Person runFrom: to:], 在每一個調(diào)用前都加上輸出語句

方案2

修改Person中對應(yīng)方法的實(shí)現(xiàn), 在- [Person runFrom: to:]的實(shí)現(xiàn)里, 最開始加上輸出語句

方案3

修改Person類的實(shí)現(xiàn), 在Person.m文件里加入私有的類比如 _PersonHelloWord 繼承自 Person, 修改Person的初始化操作返回 _PersonHelloWord, 然后_PersonHelloWord的實(shí)現(xiàn)里重寫- [Person runFrom: to:], 加入輸出語句, 再調(diào)用父類的方法

方案4

不修改Person類, 也不創(chuàng)建子類, 利用runtime的方案, 這里可以為Person添加一個分類, 在分類里寫一個新的方法, 然后利用方法交換的技術(shù)實(shí)現(xiàn)需求, 當(dāng)然這不算是消息轉(zhuǎn)發(fā),注意即使他媽的輸出語句是不需要參數(shù)的,但是交互的方法也必須提供

方案5

修改Person, 用消息轉(zhuǎn)發(fā)的技術(shù)去處理, 具體的介紹在方案4的代碼之后

方案6

KVO, 自己實(shí)現(xiàn)KVO的過程, 上一篇深入理解OC的運(yùn)行時(Runtime)里詳細(xì)的代碼.

?
1,2種我就不說了, 至于第3種,我想沒有人會這樣搞, 這種方案可能會用在別的情況下, 總之既然是方案, 那就沒有好壞之分, 只有適用和不適用之說, 第4種我下面簡單給出偽代碼, 第5種要重點(diǎn)探討的, 第6種會介紹一下,給出核心代碼

方案4 的部分代碼

@interface Person :NSObject
- (void)runFrom:(NSString*)addressStart to:(NSString*)addressEnd;
@end

@implementation Person
- (void)runFrom:(NSString*)addressStart to:(NSString*)addressEnd{
  Log("走啊走,走啊走,走啊走!");
}
@end

@interface Person(HelloWorld)
+ (void)helloWorldInit;
@end

@implementation Person(HelloWorld)
+ (void)helloWorldInit{
static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
       Method originM = class_getInstanceMethod(self, @selector(runFrom:to:));
       Method newM =  class_getInstanceMethod(self, @selector(helloworld: to:));
      ////這里不需要考慮 replace的問題([詳見上一篇里方法交換的部分)

        method_exchangeImplementations(originM,newM);
    });
}

- (void)helloworld:(NSString*)cao to:(NSString*)nima{
  Log("產(chǎn)品有病啊, 輸出一句hello world, 日!");
  [self helloworld:cao to:nima];
}
@end

方案5 的實(shí)現(xiàn)方案介紹

0 $\color{#ff0000}{首先先不考慮返回值是結(jié)構(gòu)體或者浮點(diǎn)數(shù)的情況, 后面會講的}$

1 要實(shí)現(xiàn)消息轉(zhuǎn)發(fā), 在正常sel存在IMP的情況下, 如果不做處理, 是不會進(jìn)入轉(zhuǎn)發(fā)流程的, 所以要做的事情是手動代碼控制, 進(jìn)入轉(zhuǎn)發(fā)流程

手動進(jìn)入轉(zhuǎn)發(fā)流程有多種方案, 但原理都是修改sel的IMP(這個runtime提供了接口)
1.1 讓當(dāng)前的sel指向一個和sel原始IMP簽名不一樣的函數(shù)或block, 因?yàn)楹灻粚? 找不到實(shí)現(xiàn)進(jìn)入轉(zhuǎn)發(fā)
1.2 直接讓sel指向系統(tǒng)轉(zhuǎn)發(fā)函數(shù) _objc_msgForward, 強(qiáng)制進(jìn)入轉(zhuǎn)發(fā)

2 進(jìn)入轉(zhuǎn)發(fā)流程后, 在第三步進(jìn)行操作-[NSObject forwardInvocation:invo]

3 -[NSObject forwardInvocation:invo]會將函數(shù)簽名和參數(shù)類型,返回類型, 消息接收者等包裝到invo中

4 我們要將當(dāng)前的sel, 即runFrom:to: 通過 invo 指定一個新的 newTarget對象, 讓這個newTarget 去執(zhí)行剩下的操作

5 newTarget 執(zhí)行 runFrom:to:, 首先輸出 hello wrold, 然后再想辦法回調(diào)原來的實(shí)現(xiàn)

6 所以第4步中, 在指定給newTarget的時候, 要將當(dāng)前對象eg:originalTarget傳遞給newTarget, 因?yàn)榧僭O(shè) newTarget能調(diào)用到原來的 runFrom:to:, 但是原始的runFrom:to:里可能通過 originalTarget來獲取相關(guān)的成員變量等信息, 這就要求了 newTarget在回調(diào)原來的方法時要原封不動的通過 [originalTarget runFrom:arg0 to:arg1]的方式去調(diào)用,這不需要傳遞參數(shù), 因?yàn)檗D(zhuǎn)發(fā)給newTarge的 runFrom:to:時,參數(shù)也傳遞了過來

7 第6步的分析又出現(xiàn)新的問題, 就是 [originalTarget runFrom:arg0 to:arg1] 會直接進(jìn)入消息轉(zhuǎn)發(fā), 因?yàn)樯厦嬉呀?jīng)說了, originalTarget的 runFrom:to:已經(jīng)被替換成了_objc_msgForward, 那怎么解決呢

8 第7步解決的方案, 那只有在將 runFrom:to的IMP替換為 _objc_msgForward之前, 就先記錄下來, 然后在 4步里創(chuàng)建newTarget的時候, 將IMP賦值給newTarget, 這樣newTarget可以直接調(diào)用
IMP(newTarget.originalTarget, NSSelectorFromeString(@"runFrom:to:"), arg0,arg1)

9 反思, 上述流程里是靜態(tài)創(chuàng)建了一個轉(zhuǎn)發(fā)對象newTarget, 那么newTarget的類型,即類的設(shè)計可以考慮靜態(tài)xcode的方式去創(chuàng)建, 也可以考慮動態(tài)創(chuàng)建, 那既然這里講的是runtime, 那就用runtime來創(chuàng)建類, 豈不是逼格更高?!!

10 選擇方案, 動態(tài)創(chuàng)建當(dāng)前類Person的子類, 然后添加子類的 runFrom:to:的IMP, 而且動態(tài)創(chuàng)建的子類要有擴(kuò)充的內(nèi)存, 用來添加一個元素的對象originalTarget, 這里就用到了 runtime的 add_Var的技巧了, 具體流程圖如下:(有點(diǎn)丑,但不要糾結(jié))

Snip20190518_1.png

核心代碼

@interface Person : NSObject
@property (nonatomic,strong) NSString* name;

- (void)runFrom:(NSString*)startAddStr to:(NSString*)endAddStr;
@end



@implementation Person
- (void)runFrom:(NSString*)startAddStr to:(NSString*)endAddStr{
    NSLog(@"%@正在run... 從%@ 到 %@",self.name,startAddStr,endAddStr);
}


+ (void)initialize{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [self helloRegisterMethod];
    });

}

#pragma mark - 每個對象都調(diào)換
+ (void)helloRegisterMethod{

    ////找到目標(biāo)方法
    SEL tarSEL = sel_getUid("runFrom:to:");
    Method tarM = class_getInstanceMethod(self, tarSEL);

    ////如果找到
    if (tarM) {
        ///子類的類名 當(dāng)前類的名字 + _ + subClass
        NSString* subClass = [NSStringFromClass(self) stringByAppendingFormat:@"_subClass"];

        ///創(chuàng)建子類 順便給一個var的空間, 用來保存轉(zhuǎn)發(fā)前的父類的實(shí)例對象, 目的是調(diào)用父類的實(shí)現(xiàn)的時候, 將這個對象傳給IMP, 保證原來的方法中做的事情不會被更改
        Class sub = objc_allocateClassPair(self, subClass.UTF8String, sizeof(void*));

        if (sub) {
            /////這里先獲取到IMP的地址, 如果在block內(nèi)部獲取, 不知道為什么獲取的是 _objc_msgForward的地址
            IMP org = method_getImplementation(tarM);

            ////添加一個var
            NSString* varName = [NSStringFromClass(self) stringByAppendingFormat:@"_sub_%@",NSStringFromSelector(tarSEL)];
            ///這里解釋下第3g 參數(shù), 內(nèi)存對齊的問題, 他的值與 要添加var的類型有關(guān), 也和cpu的架構(gòu)有關(guān),如果是指針, 則傳log2(sizeof(type*)), 官方文檔說的很清楚
            class_addIvar(sub,
                          varName.UTF8String,
                          sizeof(void*),
                          log2(sizeof(void*)),
                          @encode(NSString*));


            ////為子類添加 一個同樣的sel的實(shí)現(xiàn), 相當(dāng)于是覆蓋了父類
            bool addMethod = class_addMethod(sub, tarSEL, imp_implementationWithBlock(^void(id obj,NSString* arg1,NSString* arg2){
                ///先輸出hello world
                NSLog(@"hello world!");

                NSString* varName = [NSStringFromClass(self.class) stringByAppendingFormat:@"_sub_%@",NSStringFromSelector(tarSEL)];
                Ivar var = class_getInstanceVariable(sub, varName.UTF8String);
                if (var) {
                    ///再調(diào)用原始的imp
                    org(object_getIvar(obj, var),tarSEL,arg1,arg2);
                }


            }), method_getTypeEncoding(tarM));
            if (addMethod) {
                NSLog(@"添加成功");
            }

            ///注冊子類
            objc_registerClassPair(sub);

            class_replaceMethod(self, tarSEL, _objc_msgForward, method_getTypeEncoding(tarM));

        }
    }
}
- (void)forwardInvocation:(NSInvocation *)anInvocation{


    NSString* subClass = [NSStringFromClass(self.class) stringByAppendingFormat:@"_subClass"];
    Class sub = objc_getClass(subClass.UTF8String);
    if (sub) {
        id subObj = [sub new];

         NSString* varName = [NSStringFromClass(self.class) stringByAppendingFormat:@"_sub_%@",NSStringFromSelector(anInvocation.selector)];
        Ivar var = class_getInstanceVariable(sub, varName.UTF8String);
        if (var) {
            object_setIvar(subObj, var, anInvocation.target);
        }

        return [anInvocation invokeWithTarget:subObj];

    }

}
@end

方案6 的實(shí)現(xiàn)

在Person里加一個類方法, 最好在Person初始化或者第一次用的的時候調(diào)用
在這個類方法中像上一篇實(shí)現(xiàn)KVO的原理一樣, 只不過這里不是替換setter,這里是替換 runFrom:to:
新的實(shí)現(xiàn)里先輸出 hello wrold, 然后調(diào)用父類的實(shí)現(xiàn)
這里要注意的一點(diǎn)是,怎么調(diào)用父類的代碼, 這里先插入一段關(guān)于super調(diào)用的問題

super代表的僅僅是編譯器指令, 并不是一個實(shí)體的對象, 比如 [super callFun:arg0], 代碼解析如下

///我們寫的代碼
[super callFun:arg0];

///最后編譯器編譯成
objc_msgSendSuper(tmpSuper->receiver, callFun, arg0)

///查看objc_msgSendSuper的定義
objc_msgSendSuper(struct objc_super * _Nonnull super, SEL  _Nonnull op, ...)


///查看接頭體的定義 
struct objc_super {
   __unsafe_unretained _Nonnull id receiver;

#if !defined(__cplusplus)  &&  !__OBJC2__
    __unsafe_unretained _Nonnull Class class;
#else
    __unsafe_unretained _Nonnull Class super_class;
#endif
        };

//參數(shù)1 代表消息接收者, 參數(shù)2代表superClass的類對象
//編譯器創(chuàng)建臨時的tmpSuper偽代碼如下
struct objc_super* tmpSuper = malloc(sizeof(struct objc_super));
tmpSuper->receiver = self;
tmpSuper->super_class =  class_getSuperclass( object_getClass(self) );


///然后將創(chuàng)建好的 tmpSuper傳給 objc_msgSendSuper
objc_msgSendSuper(tmpSuper, callFun, arg0);

///objc_msgSendSuper的內(nèi)部會根據(jù) tmpSuper的 super_class, 找到父類類對象的地址
/// 然后去方法列表里尋找方法, 找到方法之后eg:findIMP, 就會直接通過IMP調(diào)用
findIMP(tmpSuper->receiver, callFun, arg0);

///所以很多面試?yán)飭柕?[super class], 返回的class是什么類型, 其實(shí)就像上面說的過程一樣,最后接收消息的對象始終沒有變, 所以還是當(dāng)前的類
///有的文檔說objc_msgSendSuper的內(nèi)部在找到方法的時候, 會再次調(diào)用 objc_msgSend(tmpSuper->receiver, callFun, arg0)
///我想應(yīng)該不是這樣, 這樣和 [self callFun:arg0] 沒有區(qū)別了, 因?yàn)閟uper表示到父類里找實(shí)現(xiàn)
///調(diào)用父類里處理的邏輯, 主要是和self覆蓋的callFun: 分開來, 所以我認(rèn)為是找到findIMP后, 直接執(zhí)行了

free(tmpSuper);

需求實(shí)現(xiàn)核心代碼

 Class reallyClass = object_getClass(self);

    NSString* tmpClassName = [_ClassPrefix stringByAppendingString:NSStringFromClass(reallyClass)];

    ///創(chuàng)建新的class
    Class newClass = objc_allocateClassPair(reallyClass, tmpClassName.UTF8String, 0);

    ///將Person的isa指向新建的類
    object_setClass(self, newClass);

    class_addMethod(newClass, NSSelectorFromString(@"runFrom:to:"), imp_implementationWithBlock(^void(__weak id obj, id value1, id value2){
        NSLog(@"hello world");
      
         ////自己構(gòu)建objc_msgSendSuper的第1個結(jié)構(gòu)體
        struct objc_super tmpSuper = {
              obj,
              class_getSuperclass( object_getClass(obj) );
        };
        objc_msgSendSuper(&tmpSuper, NSSelectorFromString(@"runFrom:to:"), value1, value2)

    }), "v@:@");
    objc_registerClassPair(newClass);

上述是為整個類替換掉! 能不能只指定某個對象, 其他對象不影響呢!!, 其實(shí)上一篇的KVO實(shí)現(xiàn)就是針對某個對象的, 其他對象不受影響

場景2 和上述需求一樣, 監(jiān)聽某個方法, 在方法執(zhí)行之后或之前做事情, 但是不同的是, 場景2要求只監(jiān)聽某些對象, 沒有被監(jiān)聽的對象不影響

比如Car這個類, 監(jiān)聽方法 runFrom:to:, 希望在這個方法執(zhí)行后, 再輸出一句 洗車, 但是只是Car的實(shí)例 car1會改變動作, 其他的car2, car3. car4等不受影響

對比場景1

? 和場景1不一樣的地方是, 這里只針對某些對象, 有點(diǎn)像上一篇的KVO(深入理解OC的運(yùn)行時(Runtime)), 這里也有幾種對應(yīng)關(guān)系:
? 1VS1 比如 vc1 想監(jiān)聽car1的這個動作, 然后在car1執(zhí)行完方法后, 做自己的事情
? 1VS多, 比如view1也想像VC一樣監(jiān)聽 car1, 做自己的操作
? 多VS1 VC想同時監(jiān)聽 car1, car2
.... 總之和kvo的性質(zhì)一樣, 但是這里的實(shí)現(xiàn)和kvo有所不同

解決方案選擇

利用runtime的進(jìn)行轉(zhuǎn)發(fā), 用實(shí)現(xiàn)KVO一樣的原理, 但是這里是不再改變原有的類, 代碼如下

Car定義

@interface Car : NSObject
/** 車牌號*/
@property(strong, nonatomic) NSString* licence;
- (void)runFrom:(NSString*)start to:(NSString*)end;
@end


@implementation
- (void)runFrom:(NSString*)start to:(NSString*)end{
    NSLog(@"車牌是:%@ 從 %@ 開到了 %@",self.licence, start, end);
}
@end

全局字典的格式


 @{
    @"對象1的hash字符串":@{  對象1相關(guān)的信息字典

        @"sel1字符串":@{    對象1的 sel1 相關(guān)信息的字

            @"before": @[block1, block2, ...].multable
            @"replace": @[block1, block2, ...].multable
            @"after":@[block1,block2, ... ].multable

        }.mutable,




        @"sel2字符串":@{    對象1的 sel2 相關(guān)信息的字典
            ///和sel1同樣的結(jié)構(gòu)
        }.mutable,




        ...


    }.multable,



 @"對象2的hash字符串":@{
    和對象1同樣的結(jié)構(gòu)


 }.multable

 }.multable

轉(zhuǎn)發(fā)分類相關(guān)宏的頭文件


#ifndef LBForwardToolMacro_h
#define LBForwardToolMacro_h

#ifdef __OBJC__
#define LB_CAT(A,B) A##B

#pragma mark - LBF error macro
#define LBFEC(_C) LB_CAT(LBFEC,_C)
#define LBFOT(_V) LB_CAT(LBFOT, _V)

#endif

錯誤類的定義


#import <Foundation/Foundation.h>

#import "LBForwardType.h"


#define TimeBegin_ 2000

/** LBForwardErrorCode */
typedef NS_ENUM(int,LBFEC) {
    /** 其他錯誤 */
    LBFEC(Other) = INT_MIN,

    /** 回調(diào)不能空 */
    LBFEC(EmptyOperation) = TimeBegin_,

    /** sel不能空 */
    LBFEC(EmptySEL),

    /** delloc的監(jiān)聽時間點(diǎn)必須是調(diào)用dealloc之前 */
    LBFEC(DellocTime),

    /** 禁止監(jiān)聽alloc */
    LBFEC(AllocForbid),

    /** 禁止監(jiān)聽initXXXX */
    LBFEC(InitForbid),

    /** 禁止監(jiān)聽ARC相關(guān)的 內(nèi)存管理 */
    LBFEC(ARCForbid),

    /** 禁止監(jiān)聽轉(zhuǎn)函數(shù) forwardInvocation: */
    LBFEC(SYSForward),

    /** 沒有錯誤 */
    LBFEC(NoError),
};

#undef TimeBegin_



NS_ASSUME_NONNULL_BEGIN

@interface LBForwardError : NSObject
/** 錯誤碼 */
@property (nonatomic,readonly) LBFEC eCode;

/** 錯誤描述 */
@property (nonatomic,strong) NSString* eDes;

+ (instancetype)lbEWithCode:(LBFEC)code;

@property (nonatomic,copy,readonly) void (^otherErrorDes)(NSString* _Nonnull des);

+ (instancetype)lbOEWithDes:(NSString*)des;
@end

NS_ASSUME_NONNULL_END

#define LBError(_C) [LBForwardError lbEWithCode:(_C)]



@implementation LBForwardError
+ (instancetype)lbEWithCode:(LBFEC)code{
    return [[self alloc] initWithCode:code];
}


- (instancetype)initWithCode:(LBFEC)code{
    if (self = [super init]) {
        self->_eDes = [self switchCode:code];
    }
    return self;
}


- (NSString*)switchCode:(LBFEC)code{
    _eCode = code;
    return [LBForwardError switchCode:code];
}

+ (NSString*)switchCode:(LBFEC)code{

    switch (code) {
        case LBFECEmptyOperation: return @"回調(diào)不能空";

        case LBFECEmptySEL: return @"原SEL不能空";

        case LBFECDellocTime:return @"回調(diào)必須在調(diào)用dealloc之前";

        case LBFECAllocForbid:return @"alloc 不能監(jiān)聽";

        case LBFECInitForbid: return @"initXXX 不能監(jiān)聽";

        case LBFECARCForbid: return @"ARC(retain release, autoRelease) 不能監(jiān)聽";

        case LBFECSYSForward:return @"禁止監(jiān)聽forwardInvocation:";

        case LBFECNoError: return @"no error";


        default:return @"其他錯誤";
    }
}

+ (instancetype)lbOEWithDes:(NSString*)des{
    LBForwardError* error = [self lbEWithCode:LBFECOther];

    if (des.length)
        error->_eDes = [des copy];

    return error;
}
@end

這個類主要的作用是注冊監(jiān)聽方法的時候, 出錯的描述

轉(zhuǎn)發(fā)的分類頭文件

#import "LBForwardType.h"


#define TimeBegin_ 3000

/** LBForwardOperationTime */
typedef enum: NSInteger{
    /** 在調(diào)用方法之前 回調(diào) */
    LBFOT(Before) = TimeBegin_,

    /** 替換之前的方法 */
    LBFOT(Replace),

    /** 調(diào)用完之前的方法后 再回調(diào) */
    LBFOT(After)
}LBFOT;

#undef TimeBegin_



@class LBForwardError;
typedef void(^LBFEBlock)(LBForwardError* _Nonnull error);


NS_ASSUME_NONNULL_BEGIN

@interface NSObject (LBForward)

/**
 對self的方法進(jìn)行監(jiān)聽, 在指定的time做自己的操作

 @param opBlock 你的操作 block, 簽名格式要對應(yīng)sel block的第一個參數(shù) == self, 后面開始是 sel的參數(shù)列表, block里沒有傳sel出來
 @param oSel 原方法的sel
 @param time 操作的時間點(diǎn)
 @param error 錯誤說明

 PS: 如果error為空 可能會拋異常, 異常里的 userInfo[@"error"] == LBForwardError
 */
- (void)lbf_hookOperationBlock:(id)opBlock
                   originalSel:(SEL)oSel
                   executeTime:(LBFOT)time
                         catch:(LBFEBlock _Nullable)error;

- (void)lbf_resign;
- (void)lbf_resignSEL:(SEL)oSel;


- (void)lbf_resignSEL:(SEL)oSel
          executeTime:(LBFOT)time;
@end

NS_ASSUME_NONNULL_END

轉(zhuǎn)發(fā)的分類的實(shí)現(xiàn)

#import "NSObject+LBForward.h"

#import <objc/message.h>

#import "LBForwardError.h"



#pragma mark - macors
#define LB_FORWARD_SET_OP_B_KEY     @"before"
#define LB_FORWARD_SET_OP_R_KEY     @"replace"
#define LB_FORWARD_SET_OP_A_KEY     @"after"

#define LB_FORWARD_SET_SELF_CAPACITY  5
#define LB_FORWARD_SET_SEL_CAPACITY   3
#define LB_FORWARD_SET_OP_CAPACITY  2



#define LB_HOOK_LOCK_KEY @"registerLock"

#define SYS_SELF_DEALLOC @"dealloc"
#define SYS_SELF_ARC_RT  @"retain"
#define SYS_SELF_ARC_RC  @"retainCount"
#define SYS_SELF_ARC_RL  @"release"
#define SYS_SELF_ARC_AR  @"autorelease"
#define SYS_SELF_FORWARD @"forwardInvocation:"
#define SYS_SELF_PREFIX_INIT @"init"

#define LB_HOOK_CLASS_PREFIX @"LBF_CLASS_"
#define LB_HOOK_SEL_PREFIX   @"LBF_SEL_"


#define LB_ERROR_TITLE @"出錯, 請看異常里的userinfo[@\"error\"] LBForwardError相關(guān)的報錯"
#define LB_Throw(_info) @throw [NSException exceptionWithName:LB_ERROR_TITLE reason:@"" userInfo:@{@"error":_info}]


#define LB_FORWARD_PARAM_NAME_OP    opBlock

#define LB_FORWARD_PARAM_NAME_SEL   oSel

#define LB_FORWARD_PARAM_NAME_TIME  workTime


#define LB_FORWARD_PARAM_NAME_E         registerError
#define LB_FORWARD_PARAM_NAME_E_TYPE    (void(^)(LBForwardError*))LB_FORWARD_PARAM_NAME_E


#pragma mark - block的結(jié)構(gòu)
typedef struct LBBlockLayout LBBlockLayout;


struct LBBlockLayout{
    void *isa;                      ///block指向的類, 這里oc是為了統(tǒng)一, 因?yàn)楫?dāng)一個參數(shù)是id的時候, 可以傳任意的block,而且還可以通過 NSInvocation 指定target, 設(shè)置好簽名參數(shù)調(diào)用block的實(shí)現(xiàn)

    int flags;                      ///標(biāo)記
    int reserved;
    void (*invoke)(void *, ...);
    struct block_descriptor {
        unsigned long int reserved;
        unsigned long int size;
        void (*copy)(void *dst, void *src);             // (1<<25)
        void (*dispose)(void *src);
        const char *signature;                          // (1<<30)
    } *descriptor;
};

typedef enum:int{
    LBBlockFlagsCopyDispose = (1 << 25),
    LBBlockFlagsIsGlobal = (1 << 28),
    LBBlockFlagsHasSignature = (1 << 30)
} LBBlockFlag;

typedef NSNumber* LBForwardIMPAdd;



#pragma mark - 全局的Map
#define LB_FORWARD_SET_CAPACITY 20
static NSMutableDictionary* LB_FORWARD_SET(){
    static NSMutableDictionary* dic_;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        dic_ = [NSMutableDictionary dictionaryWithCapacity:LB_FORWARD_SET_CAPACITY];
    });
    return dic_;
}
#define LB_FORWARD_SET LB_FORWARD_SET()




#pragma mark - self相關(guān)信息的key
static inline NSString* LB_FORWARD_SET_SELF_KEY(id self){
    if(!object_isClass(self))
        return [NSString stringWithFormat:@"%ld",[self hash]];
    return [NSString stringWithFormat:@"%p",self];
}
#define _LB_FORWARD_SET_SELF_KEY LB_FORWARD_SET_SELF_KEY(self)
#define _LB_FORWARD_SET_SELF     LB_FORWARD_SET[_LB_FORWARD_SET_SELF_KEY]



#pragma mark - sel 相關(guān)信息的key
static inline NSString* LB_FORWARD_SET_SEL_KEY(SEL LB_FORWARD_PARAM_NAME_SEL){
    return NSStringFromSelector(LB_FORWARD_PARAM_NAME_SEL);
}
#define _LB_FORWARD_SET_SEL_KEY LB_FORWARD_SET_SEL_KEY(LB_FORWARD_PARAM_NAME_SEL)
#define _LB_FORWARD_SET_SEL     _LB_FORWARD_SET_SELF[_LB_FORWARD_SET_SEL_KEY]


#define _LB_FORWARD_SET_OP_B    _LB_FORWARD_SET_SEL[LB_FORWARD_SET_OP_B_KEY]
#define _LB_FORWARD_SET_OP_R    _LB_FORWARD_SET_SEL[LB_FORWARD_SET_OP_R_KEY]
#define _LB_FORWARD_SET_OP_A    _LB_FORWARD_SET_SEL[LB_FORWARD_SET_OP_A_KEY]



#pragma mark - inline functions
#pragma mark - 快速根據(jù)code創(chuàng)建錯誤信息
static inline LBForwardError* _LB_FORWARD_ERROR(LBFEC code){
    return [LBForwardError lbEWithCode:code];
}




#pragma mark - 快速根據(jù)des創(chuàng)建 其他錯誤信息的error
static inline LBForwardError* _LB_FORWARD_OTHER_E(NSString* des){
    return [LBForwardError lbOEWithDes:des];
}





#pragma mark - 檢查當(dāng)前的對象是否是動態(tài)創(chuàng)建的class
static inline bool _LB_FORWARD_CLASS_IS_DYNAMIC(id self){
    return [NSStringFromClass(object_getClass(self)) hasPrefix:LB_HOOK_CLASS_PREFIX];
}
#define _LB_FORWARD_CLASS_IS_DYNAMIC_VALUE _LB_FORWARD_CLASS_IS_DYNAMIC(self)





#pragma mark - 快速獲取sel的簽名對象(對象方法)
static inline NSMethodSignature* _LB_FORWARD_SEL_ORIGINAL_SIGNA(id self, SEL LB_FORWARD_PARAM_NAME_SEL){
    if (object_isClass(self))
        return [self instanceMethodSignatureForSelector:LB_FORWARD_PARAM_NAME_SEL];

    return [self methodSignatureForSelector:LB_FORWARD_PARAM_NAME_SEL];
}
#define _LB_FORWARD_SEL_ORIGINAL_SIGNA_VALUE _LB_FORWARD_SEL_ORIGINAL_METHOD(self,LB_FORWARD_PARAM_NAME_SEL)





#pragma mark - 快速獲取sel的Method(對象方法)
static inline Method _LB_FORWARD_SEL_ORIGINAL_METHOD(id self, SEL LB_FORWARD_PARAM_NAME_SEL){
    return class_getInstanceMethod(object_getClass(self), LB_FORWARD_PARAM_NAME_SEL);
}
#define _LB_FORWARD_SEL_ORIGINAL_METHOD_VALUE _LB_FORWARD_SEL_ORIGINAL_METHOD(self,LB_FORWARD_PARAM_NAME_SEL)





#pragma mark - 快速獲取sel的簽名(c字符串)
static inline const char* _LB_FORWARD_SEL_ORIGINAL_ENCODE(id self, SEL LB_FORWARD_PARAM_NAME_SEL){
    return method_getTypeEncoding(_LB_FORWARD_SEL_ORIGINAL_METHOD_VALUE);
}
#define _LB_FORWARD_SEL_ORIGINAL_ENCODE_VALUE _LB_FORWARD_SEL_ORIGINAL_ENCODE(self,LB_FORWARD_PARAM_NAME_SEL)



#pragma mark - 判斷是不是 initXXX的方法
static inline bool _LB_FORWARD_SEL_IS_INITIALIZE(id self, SEL LB_FORWARD_PARAM_NAME_SEL){
    NSString* selString = NSStringFromSelector(LB_FORWARD_PARAM_NAME_SEL);
    if (selString.length)
        if ([selString hasPrefix:SYS_SELF_PREFIX_INIT])
            return true;

    return false;
}




#pragma mark - 快速獲取當(dāng)前對象 要動態(tài)被創(chuàng)建的類名
static inline NSString* _LB_FORWARD_DYNAMIC_CLASS_NAME(id self){
    return [LB_HOOK_CLASS_PREFIX stringByAppendingString:NSStringFromClass(object_getClass(self))];
}
#define _LB_FORWARD_DYNAMIC_CLASS_NAME_VALUE _LB_FORWARD_DYNAMIC_CLASS_NAME(self)




#pragma mark - 快速獲取當(dāng)前動態(tài)創(chuàng)建的子類 被添加的新的sel的字符串
static inline NSString* _LB_FORWARD_DYNAMIC_SEL_NAME(SEL LB_FORWARD_PARAM_NAME_SEL){
    return [LB_HOOK_SEL_PREFIX stringByAppendingString:NSStringFromSelector(LB_FORWARD_PARAM_NAME_SEL)];
}
#define _LB_FORWARD_DYNAMIC_SEL_NAME_VALUE _LB_FORWARD_DYNAMIC_SEL_NAME(LB_FORWARD_PARAM_NAME_SEL)



#pragma mark - 根據(jù)操作的枚舉值返回對應(yīng)的key
static inline NSString* _LB_FORWARD_SEL_OP_TIME(LBFOT LB_FORWARD_PARAM_NAME_TIME){
    switch (LB_FORWARD_PARAM_NAME_TIME) {
        case LBFOTBefore:return LB_FORWARD_SET_OP_B_KEY;

        case LBFOTReplace:return LB_FORWARD_SET_OP_R_KEY;

        case LBFOTAfter:return LB_FORWARD_SET_OP_A_KEY;

        default:return nil;
    }
}
#define _LB_FORWARD_SEL_OP_TIME_VALUE _LB_FORWARD_SEL_OP_TIME(LB_FORWARD_PARAM_NAME_TIME)





#pragma mark - 獲取sel的imp 這時候self已經(jīng)指向動態(tài)的子類了
static inline IMP _LB_FORWARD_SEL_ORIGINAL_IMP(id self, SEL LB_FORWARD_PARAM_NAME_SEL){
    IMP oImp = class_getMethodImplementation(object_getClass(self), LB_FORWARD_PARAM_NAME_SEL);
    oImp = !oImp ? nil:class_getMethodImplementation(object_getClass(self), LB_FORWARD_PARAM_NAME_SEL);
    return oImp;
}
#define _LB_FORWARD_SEL_ORIGINAL_IMP_VALUE _LB_FORWARD_SEL_ORIGINAL_IMP(self,LB_FORWARD_PARAM_NAME_SEL)





#pragma mark - 輔助函數(shù)
#pragma mark - 判斷block是否是合法的簽名
static bool _LB_FORWARD_OP_AVAILABLE_SIGNATURE(id self, SEL LB_FORWARD_PARAM_NAME_SEL, id LB_FORWARD_PARAM_NAME_OP);




static void LB_FORWARD_ENTRANCE(id self, SEL invoSel, NSInvocation* sysInVo);



#pragma mark - 類實(shí)現(xiàn)
@implementation NSObject (LBForward)
- (void)lbf_hookOperationBlock:(id)LB_FORWARD_PARAM_NAME_OP
                   originalSel:(SEL)LB_FORWARD_PARAM_NAME_SEL
                   executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME
                         catch:LB_FORWARD_PARAM_NAME_E_TYPE{

    @synchronized (LB_HOOK_LOCK_KEY) {

        if (LB_FORWARD_PARAM_NAME_E_TYPE)
            return [self _lbf_hookOperationBlock:LB_FORWARD_PARAM_NAME_OP
                                     originalSel:LB_FORWARD_PARAM_NAME_SEL
                                     executeTime:LB_FORWARD_PARAM_NAME_TIME
                                           catch:LB_FORWARD_PARAM_NAME_E];

        [self _lbf_hookOperationBlock:LB_FORWARD_PARAM_NAME_OP
                          originalSel:LB_FORWARD_PARAM_NAME_SEL
                          executeTime:LB_FORWARD_PARAM_NAME_TIME];
    }
}



#pragma mark - 主方法里registerError 不為空的時候的流程
- (void)_lbf_hookOperationBlock:(id)LB_FORWARD_PARAM_NAME_OP
                    originalSel:(SEL)LB_FORWARD_PARAM_NAME_SEL
                    executeTime:(int)LB_FORWARD_PARAM_NAME_TIME
                          catch:LB_FORWARD_PARAM_NAME_E_TYPE{

    [self checkParmsWithOperationBlock:LB_FORWARD_PARAM_NAME_OP
                           originalSel:LB_FORWARD_PARAM_NAME_SEL
                           executeTime:LB_FORWARD_PARAM_NAME_TIME
                                 catch:LB_FORWARD_PARAM_NAME_E];



    ////注冊相關(guān)信息
    [self registerInfoWithOperationBlock:LB_FORWARD_PARAM_NAME_OP
                             originalSel:LB_FORWARD_PARAM_NAME_SEL
                             executeTime:LB_FORWARD_PARAM_NAME_TIME];
}

#pragma mark - 主方法里registerError為空的時候的流程
- (void)_lbf_hookOperationBlock:(id)LB_FORWARD_PARAM_NAME_OP
                    originalSel:(SEL)LB_FORWARD_PARAM_NAME_SEL
                    executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{


    [self checkParmsWithOperationBlock:LB_FORWARD_PARAM_NAME_OP
                           originalSel:LB_FORWARD_PARAM_NAME_SEL
                           executeTime:LB_FORWARD_PARAM_NAME_TIME
                                 catch:nil];



    ////注冊相關(guān)信息
    [self registerInfoWithOperationBlock:LB_FORWARD_PARAM_NAME_OP
                             originalSel:LB_FORWARD_PARAM_NAME_SEL
                             executeTime:LB_FORWARD_PARAM_NAME_TIME];

}

#pragma mark - 參數(shù)相關(guān)檢查
- (void)checkParmsWithOperationBlock:(id)LB_FORWARD_PARAM_NAME_OP
                         originalSel:(SEL)LB_FORWARD_PARAM_NAME_SEL
                         executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME
                               catch:LB_FORWARD_PARAM_NAME_E_TYPE{
    ///空的操作
    if (!LB_FORWARD_PARAM_NAME_OP){
        !LB_FORWARD_PARAM_NAME_E ? : LB_FORWARD_PARAM_NAME_E(_LB_FORWARD_ERROR(LBFECEmptyOperation));

        if(!LB_FORWARD_PARAM_NAME_E)LB_Throw(_LB_FORWARD_ERROR(LBFECEmptyOperation));
    }






    ///空的sel
    if (!LB_FORWARD_PARAM_NAME_SEL){
        !LB_FORWARD_PARAM_NAME_E ? : LB_FORWARD_PARAM_NAME_E(_LB_FORWARD_ERROR(LBFECEmptySEL));

        if(!LB_FORWARD_PARAM_NAME_E)LB_Throw(_LB_FORWARD_ERROR(LBFECEmptySEL));
    }






    ///沒有具體的實(shí)現(xiàn)
    if(!_LB_FORWARD_SEL_ORIGINAL_SIGNA(self, LB_FORWARD_PARAM_NAME_SEL)){
        NSString* errorStr = [NSString stringWithFormat:@"對象:%p(%@) 的%@ 沒有對應(yīng)的實(shí)現(xiàn)",
                              self,object_getClass(self),
                              NSStringFromSelector(LB_FORWARD_PARAM_NAME_SEL)];

        !LB_FORWARD_PARAM_NAME_E ? : LB_FORWARD_PARAM_NAME_E(_LB_FORWARD_OTHER_E(errorStr));

        if(!LB_FORWARD_PARAM_NAME_E)LB_Throw(_LB_FORWARD_OTHER_E(errorStr));
    }




    ///不能監(jiān)聽的方法
    LBForwardError* fobidMethod = [self fileterSEL:LB_FORWARD_PARAM_NAME_SEL
                                       executeTime:LB_FORWARD_PARAM_NAME_TIME];
    if (fobidMethod){
        !LB_FORWARD_PARAM_NAME_E ? : LB_FORWARD_PARAM_NAME_E(fobidMethod);
        if(!LB_FORWARD_PARAM_NAME_E)LB_Throw(fobidMethod);
    }



    ///簽名不符合
    if(!_LB_FORWARD_OP_AVAILABLE_SIGNATURE(self, LB_FORWARD_PARAM_NAME_SEL, LB_FORWARD_PARAM_NAME_OP)){
        NSString* errorStr = [NSString stringWithFormat:@"對象:%p(%@) 的%@ 簽名不符合, 請閱讀 \"lbf_hookOperationBlock:originalSel:executeTime:catch:\"說明",
                              self,object_getClass(self),
                              NSStringFromSelector(LB_FORWARD_PARAM_NAME_SEL)];

        !LB_FORWARD_PARAM_NAME_E ? : LB_FORWARD_PARAM_NAME_E(_LB_FORWARD_OTHER_E(errorStr));
        if(!LB_FORWARD_PARAM_NAME_E)LB_Throw(_LB_FORWARD_OTHER_E(errorStr));
    }
}



#pragma mark - 注冊相關(guān)信息
- (void)registerInfoWithOperationBlock:(id)LB_FORWARD_PARAM_NAME_OP
                           originalSel:(SEL)LB_FORWARD_PARAM_NAME_SEL
                           executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{
    Class reallyClass = [self isAvaiableClass];

    ///創(chuàng)建子類
    if (!reallyClass)
        [self createSubClassWithSEL:LB_FORWARD_PARAM_NAME_SEL
                        executeTime:LB_FORWARD_PARAM_NAME_TIME];




    ///緩存相關(guān)的信息
    [self cacheOPWithBlock:LB_FORWARD_PARAM_NAME_OP
               originalSel:LB_FORWARD_PARAM_NAME_SEL
               executeTime:LB_FORWARD_PARAM_NAME_TIME];
}


#pragma mark - 當(dāng)前類是否創(chuàng)建過子類
- (Class)isAvaiableClass{
    if (_LB_FORWARD_CLASS_IS_DYNAMIC(self)) return object_getClass(self);
    
    NSString* dynamicClassName = _LB_FORWARD_DYNAMIC_CLASS_NAME_VALUE;
    return objc_getClass(dynamicClassName.UTF8String);
}

#pragma mark - 獲取self_info(內(nèi)部會設(shè)置isa)
- (NSMutableDictionary*)cacheSelfSet{
    NSString* key = _LB_FORWARD_SET_SELF_KEY;
    NSMutableDictionary* result = [LB_FORWARD_SET objectForKey:key];
    if (!result) {
        result = [NSMutableDictionary dictionaryWithCapacity:LB_FORWARD_SET_SELF_CAPACITY];
        [LB_FORWARD_SET setObject:result forKey:key];
    }

    ///這個時候isAvaiableClass一定有值
    if (!_LB_FORWARD_CLASS_IS_DYNAMIC_VALUE)
        object_setClass(self, [self isAvaiableClass]);

    return result;
}

#pragma mark - 獲取sel_info
- (NSMutableDictionary*)cacheSelSetWith:(SEL)LB_FORWARD_PARAM_NAME_SEL
                               superSet:(NSMutableDictionary*)superSet{
    NSString* key = _LB_FORWARD_SET_SEL_KEY;
    NSMutableDictionary* result = [superSet objectForKey:key];
    if (!result) {
        result = [NSMutableDictionary dictionaryWithCapacity:LB_FORWARD_SET_SEL_CAPACITY];

        [superSet setObject:result forKey:key];
    }
    return result;
}




#pragma mark - 緩存相關(guān)信息
- (void)cacheOPWithBlock:(id)LB_FORWARD_PARAM_NAME_OP
             originalSel:(SEL)LB_FORWARD_PARAM_NAME_SEL
             executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{


    ///sel_info
    NSMutableDictionary* superSet = [self cacheSelSetWith:LB_FORWARD_PARAM_NAME_SEL
                                                 superSet:[self cacheSelfSet]];

    ///添加方法 交換方法
    [self tryAddMethodWithSEL:LB_FORWARD_PARAM_NAME_SEL
                  executeTime:LB_FORWARD_PARAM_NAME_TIME];



    NSString* key = _LB_FORWARD_SEL_OP_TIME_VALUE;

    if (key) {
        NSMutableArray* result = [superSet objectForKey:key];
        if (!result) {
            result = [NSMutableArray arrayWithCapacity:LB_FORWARD_SET_OP_CAPACITY];
            [superSet setObject:result forKey:key];
        }

        [result addObject:LB_FORWARD_PARAM_NAME_OP];
    }
}













#pragma mark - 過濾方法
- (LBForwardError*)fileterSEL:(SEL)LB_FORWARD_PARAM_NAME_SEL
                  executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{


    ///dealloc
    if(sel_isEqual(LB_FORWARD_PARAM_NAME_SEL, NSSelectorFromString(SYS_SELF_DEALLOC)))
        if(LB_FORWARD_PARAM_NAME_TIME != LBFOTBefore)
            return _LB_FORWARD_ERROR(LBFECDellocTime);


    ///arc
    if(sel_isEqual(LB_FORWARD_PARAM_NAME_SEL, NSSelectorFromString(SYS_SELF_ARC_RT)))
        return _LB_FORWARD_ERROR(LBFECARCForbid);


    if(sel_isEqual(LB_FORWARD_PARAM_NAME_SEL, NSSelectorFromString(SYS_SELF_ARC_RL)))
        return _LB_FORWARD_ERROR(LBFECARCForbid);


    if(sel_isEqual(LB_FORWARD_PARAM_NAME_SEL, NSSelectorFromString(SYS_SELF_ARC_RC)))
        return _LB_FORWARD_ERROR(LBFECARCForbid);

    if(sel_isEqual(LB_FORWARD_PARAM_NAME_SEL, NSSelectorFromString(SYS_SELF_ARC_AR)))
        return _LB_FORWARD_ERROR(LBFECARCForbid);

    if(sel_isEqual(LB_FORWARD_PARAM_NAME_SEL, NSSelectorFromString(SYS_SELF_FORWARD)))
        return _LB_FORWARD_ERROR(LBFECARCForbid);


    ///initXXX
    if(_LB_FORWARD_SEL_IS_INITIALIZE(self, LB_FORWARD_PARAM_NAME_SEL))
        return _LB_FORWARD_ERROR(LBFECInitForbid);


    return nil;

}


#pragma mark - 動態(tài)創(chuàng)建類
- (Class)createSubClassWithSEL:(SEL)LB_FORWARD_PARAM_NAME_SEL
                   executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{
    NSString* dynamicClassName = _LB_FORWARD_DYNAMIC_CLASS_NAME_VALUE;

    Class dynamicClass = objc_allocateClassPair(object_getClass(self), dynamicClassName.UTF8String, 0);

    if (dynamicClass) {
        ///將self 的 isa 指向 新建的子類
//        object_setClass(self, dynamicClass);


        ///添加一個 class方法 返回父類
#warning class方法
        objc_registerClassPair(dynamicClass);
    }

    return dynamicClass;
}


#pragma mark - 方法注冊相關(guān)
- (void)tryAddMethodWithSEL:(SEL)LB_FORWARD_PARAM_NAME_SEL
                executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{


    Class reallyClass = object_getClass(self);


    SEL subSel = NSSelectorFromString(_LB_FORWARD_DYNAMIC_SEL_NAME_VALUE);


    ///第二次雖然獲取到的是 objc_msgforward的IMP, 但是class_addMethod會添加失敗, 因?yàn)榈?次的時候已經(jīng)正確填充信息了, 所以這里不要糾結(jié)
    IMP selOImp = _LB_FORWARD_SEL_ORIGINAL_IMP_VALUE;

    ///這里的簽名 就是 原始的sel的簽名
    const char* selOEncode = _LB_FORWARD_SEL_ORIGINAL_ENCODE_VALUE;



    if (class_addMethod(reallyClass,
                        subSel,
                        selOImp,
                        selOEncode)) {


        ///將原來的方法 強(qiáng)制指向系統(tǒng)調(diào)用函數(shù), 這樣外界調(diào)用的時候就會進(jìn)入轉(zhuǎn)發(fā)
        class_replaceMethod(reallyClass,
                            LB_FORWARD_PARAM_NAME_SEL,
                            _objc_msgForward,
                            selOEncode
                            );



        ///將當(dāng)前class的 轉(zhuǎn)發(fā)函數(shù)替換到 自定義的, 方便處理
        class_replaceMethod(reallyClass,
                            @selector(forwardInvocation:),
                            (IMP)LB_FORWARD_ENTRANCE,
                            "v@:");

    }
}

#pragma mark - 注銷
- (void)lbf_resign{
    [LB_FORWARD_SET removeObjectForKey:_LB_FORWARD_SET_SELF_KEY];
}

- (void)lbf_resignSEL:(SEL)LB_FORWARD_PARAM_NAME_SEL{
    if (!LB_FORWARD_PARAM_NAME_SEL) return[self lbf_resign];

    NSMutableDictionary* self_info = _LB_FORWARD_SET_SELF;
    [self_info removeObjectForKey:_LB_FORWARD_SET_SEL_KEY];
    if(self_info.allKeys.count == 0) [self lbf_resign];
}


- (void)lbf_resignSEL:(SEL)LB_FORWARD_PARAM_NAME_SEL
          executeTime:(LBFOT)LB_FORWARD_PARAM_NAME_TIME{

    if (!LB_FORWARD_PARAM_NAME_SEL) return[self lbf_resignSEL:LB_FORWARD_PARAM_NAME_SEL];

    NSMutableDictionary* sel_info = _LB_FORWARD_SET_SEL;
    [sel_info removeObjectForKey:_LB_FORWARD_SEL_OP_TIME_VALUE];
    if (!sel_info.allKeys.count) [self lbf_resignSEL:LB_FORWARD_PARAM_NAME_SEL];
}

@end




static void LB_FORWARD_EXCUTE_OI(id self, NSInvocation* sysInvo, SEL LB_FORWARD_PARAM_NAME_SEL){
    sysInvo.selector = NSSelectorFromString(_LB_FORWARD_DYNAMIC_SEL_NAME_VALUE);
    sysInvo.target = self;
    [sysInvo invoke];
}
#define _LB_FORWARD_EXCUTE_OI() LB_FORWARD_EXCUTE_OI(self,sysInvo,LB_FORWARD_PARAM_NAME_SEL)

static void LB_FORWARD_EXCUTE_OP(NSArray* ops, NSInvocation* sysInvo){

    void* arg = NULL;
    [sysInvo getArgument:&arg atIndex:0];
    [sysInvo setArgument:&arg atIndex:1];

    for (int i = 0; i < ops.count; ++i) {
        sysInvo.target = ops[i];
        [sysInvo invoke];
    }
}



#pragma mark - 全局轉(zhuǎn)發(fā)函數(shù)
__unused void LB_FORWARD_ENTRANCE(id self, SEL invoSel, NSInvocation* sysInvo){
    SEL oSel = sysInvo.selector;


    ///befores block
    LB_FORWARD_EXCUTE_OP(_LB_FORWARD_SET_OP_B,sysInvo);

    ///這里的問題是 只要有一個替代的操作, 原方法就執(zhí)行不了, Aspeacts 也是同樣的情況
    if ([_LB_FORWARD_SET_OP_R count])
        LB_FORWARD_EXCUTE_OP(_LB_FORWARD_SET_OP_R, sysInvo);
    else{
        _LB_FORWARD_EXCUTE_OI();
    }


    ///after
    LB_FORWARD_EXCUTE_OP(_LB_FORWARD_SET_OP_A,sysInvo);
}




bool _LB_FORWARD_OP_AVAILABLE_SIGNATURE(id self, SEL LB_FORWARD_PARAM_NAME_SEL, id LB_FORWARD_PARAM_NAME_OP){
    LBBlockLayout* tmpBlockLayout = (__bridge LBBlockLayout *)(LB_FORWARD_PARAM_NAME_OP);
    int flags = tmpBlockLayout -> flags;

    if (flags & LBBlockFlagsHasSignature) {

        ////這2步都是指針的加減
        void* signatureAddress = (void*)(tmpBlockLayout -> descriptor) + 2 * sizeof(unsigned long);

        if (flags & LBBlockFlagsCopyDispose)
            signatureAddress += 2 * sizeof(void*);



        const char* signalStr = *((char**)signatureAddress);
        if (signalStr) {

            NSMethodSignature* blockS = [NSMethodSignature signatureWithObjCTypes:signalStr];
            NSMethodSignature* selS = _LB_FORWARD_SEL_ORIGINAL_SIGNA(self, LB_FORWARD_PARAM_NAME_SEL);

            if (!selS) return NO;


            NSInteger tmpBArgCount = blockS.numberOfArguments;

            if (tmpBArgCount > selS.numberOfArguments)
                return NO;

            if (tmpBArgCount > 1)
                if ([blockS getArgumentTypeAtIndex:1][0] != '@') return NO;


            for (NSUInteger i = 2; i < tmpBArgCount; ++i) {
                const char *methodType = [selS getArgumentTypeAtIndex:i];
                const char *blockType = [blockS getArgumentTypeAtIndex:i];

                if (!methodType || !blockType ) return NO;


                if (methodType[0] != blockType[0]) return NO;
            }

            return true;
        }
    }

    return false;
}

流程

? 1. 創(chuàng)建car1對象
? 2. 調(diào)用lbf_hookOperationBlock: originalSel: executeTime: catch:
? ? 2.1 catch一定要傳, 不然異常
? ? 2.2 檢查各個參數(shù)的是否空, 檢查sel是否實(shí)現(xiàn)和過濾相關(guān)的方法,檢查block的簽名是否和sel的一致
? ? 2.3 注冊相關(guān)信息
? ? ? ? 2.3.1 判斷是否動態(tài)創(chuàng)建過子類, 沒創(chuàng)建就創(chuàng)建子類
? ? ? ? 2.3.2 先從緩存里取相關(guān)的數(shù)據(jù)(block), 沒取到, 就創(chuàng)建, 創(chuàng)建的過程里把當(dāng)前的self的isa指向了新的類LBF_CLASS_originaclass,然后動態(tài)添加了一個新的SEL === LBF_SEL_originalSel, 并且指向了原方法的IMP,然后將原方法oSel指向了objc_msgForward, 然后將轉(zhuǎn)發(fā)函數(shù)forwardInvocation:指向了全局處理的函數(shù)LB_FORWARD_ENTRANCE, 當(dāng)調(diào)用注冊的方法的時候, 會來到全局處理的函數(shù)里, 在這里面根據(jù)記錄進(jìn)行篩選
? ? 2.4 可以調(diào)用resign相關(guān)的函數(shù)注掉監(jiān)聽

PS:這個簡單的demo,有很多問題, 只是簡單的測試了下, 里面記錄用的是全局的map, 所以要自己處理注銷的問題,如果是用runtime里的關(guān)聯(lián),那么self 被dealloc的時候會自動釋放掉之前關(guān)聯(lián)的內(nèi)存(Aspeacts), 里面沒有實(shí)現(xiàn)類方法的監(jiān)聽, 但是寫這個demo, 基本runtime的知識點(diǎn)都用到了, 包括block的簽名獲取, 怎么通過方法調(diào)用block等等

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OC的消息機(jī)制深入理解

OC的消息機(jī)制深入理解

前言

編碼相關(guān)

方法簽名

消息轉(zhuǎn)發(fā)(利用系統(tǒng)提供的接口轉(zhuǎn)發(fā))

手動觸發(fā)消息轉(zhuǎn)發(fā)(方法監(jiān)聽AOP編程)

場景1 假設(shè)現(xiàn)在的需求是項目里所有Person對象用到的地方, 只要調(diào)用了`- [Person runFrom: to:]` 都必須在調(diào)用前打印 `hello world`

解決方案選擇

方案1

方案2

方案3

方案4

方案5

方案6

方案4 的部分代碼

方案5 的實(shí)現(xiàn)方案介紹

方案6 的實(shí)現(xiàn)

上述是為整個類替換掉! 能不能只指定某個對象, 其他對象不影響呢!!, 其實(shí)上一篇的KVO實(shí)現(xiàn)就是針對某個對象的, 其他對象不受影響

場景2 和上述需求一樣, 監(jiān)聽某個方法, 在方法執(zhí)行之后或之前做事情, 但是不同的是, 場景2要求只監(jiān)聽某些對象, 沒有被監(jiān)聽的對象不影響

對比場景1

解決方案選擇

利用runtime的進(jìn)行轉(zhuǎn)發(fā), 用實(shí)現(xiàn)KVO一樣的原理, 但是這里是不再改變原有的類, 代碼如下

流程

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容

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OC的消息機(jī)制深入理解

前言

編碼相關(guān)

方法簽名

消息轉(zhuǎn)發(fā)(利用系統(tǒng)提供的接口轉(zhuǎn)發(fā))

手動觸發(fā)消息轉(zhuǎn)發(fā)(方法監(jiān)聽AOP編程)

場景1 假設(shè)現(xiàn)在的需求是 項目里所有Person對象用到的地方, 只要調(diào)用了- [Person runFrom: to:] 都必須在調(diào)用前打印 hello world

解決方案選擇

方案1

方案2

方案3

方案4

方案5

方案6

方案4 的部分代碼

方案5 的實(shí)現(xiàn)方案介紹

方案6 的實(shí)現(xiàn)

上述是為整個類替換掉! 能不能只指定某個對象, 其他對象不影響呢!!, 其實(shí)上一篇的KVO實(shí)現(xiàn)就是針對某個對象的, 其他對象不受影響

場景2 和上述需求一樣, 監(jiān)聽某個方法, 在方法執(zhí)行之后或之前做事情, 但是不同的是, 場景2要求只監(jiān)聽某些對象, 沒有被監(jiān)聽的對象不影響

對比場景1

解決方案選擇

利用runtime的進(jìn)行轉(zhuǎn)發(fā), 用實(shí)現(xiàn)KVO一樣的原理, 但是這里是不再改變原有的類, 代碼如下

流程

相關(guān)閱讀更多精彩內(nèi)容

友情鏈接更多精彩內(nèi)容

色偷偷精品伊人,欧洲久久精品,欧美综合婷婷骚逼,国产AV主播,国产最新探花在线,九色在线视频一区,伊人大交九欧美,1769亚洲,黄色成人av

場景1 假設(shè)現(xiàn)在的需求是項目里所有Person對象用到的地方, 只要調(diào)用了`- [Person runFrom: to:]` 都必須在調(diào)用前打印 `hello world`