1、圖片拉伸

QQ20171020-183930@2x.png

2、KVC的使用

KVC: Key Value Coding(鍵值編碼)

#import <Foundation/Foundation.h>
#import "XMGPerson.h"
#import "XMGDog.h"

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        /**
          取出數(shù)組中所有模型的某個(gè)屬性值
         */
        XMGPerson *person1 = [[XMGPerson alloc] init];
        person1.name = @"zhangsan";
        person1.money = 12.99;
        
        XMGPerson *person2 = [[XMGPerson alloc] init];
        person2.name = @"zhangsi";
        person2.money = 22.99;
        
        XMGPerson *person3 = [[XMGPerson alloc] init];
        person3.name = @"wangwu";
        person3.money = 122.99;
        
        NSArray *allPersons = @[person1, person2, person3];
        NSArray *allPersonName = [allPersons valueForKeyPath:@"name"];
        
        NSLog(@"%@", allPersonName);
    }
    return 0;
}

/**
 *  把模型轉(zhuǎn)成字典
 */

void test6(){
    XMGPerson *person = [[XMGPerson alloc] init];
    person.name = @"lurry";
    person.money = 21.21;
    
    NSDictionary *dict = [person dictionaryWithValuesForKeys:@[@"name", @"money"]];
    NSLog(@"%@", dict);
}


/**
 * 取值
 */
void test5(){
    XMGPerson *person = [[XMGPerson alloc] init];
    person.name = @"張三";
    person.money = 12332;
    
    // 利用kvc取值
    NSLog(@"%@ --- %.2f", [person valueForKeyPath:@"name"], [[person valueForKey:@"money"] floatValue]);
}

/**
 作用: 字典轉(zhuǎn)模型
 開(kāi)發(fā)中是不建議使用setValuesForKeysWithDictionary:
 1> 字典中的key必須在模型的屬性中找到
 2> 如果模型中帶有模型,setValuesForKeysWithDictionary不好使
 應(yīng)用場(chǎng)景: 簡(jiǎn)單的字典轉(zhuǎn)模型 ---> 框架 (MJExtention)
 */
void test4(){
    NSDictionary *dict = @{
                           @"name" :@"lurry",
                           @"money" : @189.88,
                           @"dog" : @{
                                   @"name" : @"wangcai",
                                   @"price" : @8
                                   },
                           @"books": @[
                                   @{@"name" :@"iOS快速開(kāi)發(fā)", @"price" : @1999},
                                   @{@"name" :@"iOS快速發(fā)", @"price" : @199},
                                   @{@"name" :@"iOS快開(kāi)發(fā)", @"price" : @99}
                                   ]
                           };
    XMGPerson *person = [[XMGPerson alloc] initWithDict:dict];
    NSLog(@"%@", person.dog.class);
    
    [person setValue: @{
                        @"name" : @"wangcai",
                        @"price" : @8
                        } forKeyPath:@"dog"];
}


/**
 *  利用KVC修改類(lèi)的私有成員變量(UIPageControl)
 */
void test3(){
    XMGPerson *person = [[XMGPerson alloc] init];
    //        person->_age
    // 利用KVC修改類(lèi)的私有成員變量
    [person printAge];
    [person setValue:@"88" forKeyPath:@"_age"]; // age _age
    [person printAge];
}

/**
 *  利用KVC進(jìn)行綜合賦值
 */
void test2(){
    XMGPerson *person = [[XMGPerson alloc] init];
    person.dog = [[XMGDog alloc] init];
    //        person.dog.name = @"旺財(cái)";
    
    // KVC賦值
    /*
     forKey和forKeyPath
     1>forKeyPath 包含了所有 forKey 的功能
     2>forKeyPath 進(jìn)行內(nèi)部的點(diǎn)語(yǔ)法,層層訪問(wèn)內(nèi)部的屬性
     3>注意: key值一定要在屬性中找到
     */
    //        [person.dog setValue:@"阿黃" forKey:@"name"];
    [person setValue:@"旺財(cái)" forKeyPath:@"dog.name"];
    
    NSLog(@"%@", person.dog.name);

}

/**
 *  利用KVC進(jìn)行簡(jiǎn)單賦值
 */
void test(){
    XMGPerson *person = [[XMGPerson alloc] init];
    // 常規(guī)賦值
    /*
     person.name = @"張三";
     person.age = 18;
     */
    
    // KVC賦值
    [person setValue:@"王五" forKey:@"name"];
    [person setValue:@"19" forKeyPath:@"money"]; // 自動(dòng)類(lèi)型轉(zhuǎn)換
    
    NSLog(@"%@-----%.2f", person.name, person.money);
}

3、KVO的使用

KVO: Key Value Observing (鍵值監(jiān)聽(tīng))--->當(dāng)某個(gè)對(duì)象的屬性值發(fā)生改變的時(shí)候(用KVO監(jiān)聽(tīng))

#import "ViewController.h"
#import "XMGPerson.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
 
    XMGPerson *person = [[XMGPerson alloc] init];
    person.name = @"zs";
    
    /*
     作用:給對(duì)象綁定一個(gè)監(jiān)聽(tīng)器(觀察者)
     - Observer 觀察者
     - KeyPath 要監(jiān)聽(tīng)的屬性
     - options 選項(xiàng)(方法方法中拿到屬性值)
     */
    [person addObserver:self forKeyPath:@"name" options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld context:nil];
    
    
    person.name = @"ls";
    
    person.name = @"ww";
    

    
    // 移除監(jiān)聽(tīng)
    [person removeObserver:self forKeyPath:@"name"];
}

/**
 *  當(dāng)監(jiān)聽(tīng)的屬性值發(fā)生改變
 *
 *  @param keyPath 要改變的屬性
 *  @param object  要改變的屬性所屬的對(duì)象
 *  @param change  改變的內(nèi)容
 *  @param context 上下文
 */
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context{
    NSLog(@"%@------%@------%@", keyPath, object, change);
}

@end