UIGestureRecognizer

緩解UIGestureRecognizer的操作壓力，用一個block解決掉，不同的手勢間的調(diào)用。
主要代碼

#import "UIGestureRecognizer+block.h"
#import <objc/runtime.h>
#import <objc/message.h>

static const int target_key;

@implementation UIGestureRecognizer (block)

+(instancetype)xjg_gestureRecognizerWithActionBlcok:(XJGestureBlock)block{
    return [[self alloc]initWithActionBlock:block];
}

-(instancetype)initWithActionBlock:(XJGestureBlock)block{
    self = [self init];//先init初始化成功，調(diào)用的-方法表示這個self已經(jīng)是一個實例，每次將實例和block綁定。如果用類對象綁定就只能產(chǎn)生一種效果不行~
    [self addActionBlcok:block];
    [self addTarget:self action:@selector(invoke:)];
    return self;
}

- (void)addActionBlcok:(XJGestureBlock)block{
    if(block){
        objc_setAssociatedObject(self, &target_key, block, OBJC_ASSOCIATION_COPY_NONATOMIC);
    }
}
- (void)invoke:(id)sender{
    XJGestureBlock block=objc_getAssociatedObject(self, &target_key);
    if(block)
        block(sender);
}

@end

github源碼

UIAlertView

多個alertview造成代碼冗余

//調(diào)用代碼
- (void)firstClick{
    UIAlertView *al = [[UIAlertView alloc]initWithTitle:@"first" message:@"ok" delegate:self cancelButtonTitle:@"cancle" otherButtonTitles:@"OK", nil];
    al.block = ^(UIAlertView *alert,NSUInteger index){
        if(index ==1)
            NSLog(@"001");
    };
    [al show];
}

//類別代碼
#import "UIAlertView+block.h"
#import <objc/runtime.h>
#import <objc/message.h>

@interface UIAlertView ()<UIAlertViewDelegate>

@end
@implementation UIAlertView (block)

- (void)setBlock:(JGAlertBlock)block{
    objc_setAssociatedObject(self, @selector(block), block, OBJC_ASSOCIATION_COPY_NONATOMIC);
    self.delegate = self;
}

- (JGAlertBlock)block{
    return objc_getAssociatedObject(self, @selector(block));
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
    if(self.block)
        self.block(alertView,buttonIndex);
}

@end

github源碼
看了這個風(fēng)格你就能理解為什么蘋果iOS9要廢棄alertview轉(zhuǎn)型UIAlertViewController，在多個alert實在是很難管理，好多delegate，代碼冗余。

上面是兩種不同的使用風(fēng)格，第一個在非代理情況下給不同的手勢填了了一個block。區(qū)分多個手勢
第二個在有代理情況下區(qū)分不同的alert，都是使用了associated特性。方式卻有不同。仔細思考