• 給UIBarButtonItem添加一個Block分類

#import <UIKit/UIKit.h>

@interface UIBarButtonItem (BlockSupport)

- (nullable instancetype)initWithTitle:(nullable NSString *)title style:(UIBarButtonItemStyle)style andBlock:(void(^)())clickBlock;

@end

#import "UIBarButtonItem+BlockSupport.h"
#import <objc/runtime.h>

const char *barbuttonItemBlockKey = "barbuttonItemBlockKey";

@implementation UIBarButtonItem (BlockSupport)

- (instancetype)initWithTitle:(nullable NSString *)title style:(UIBarButtonItemStyle)style andBlock:(void(^)())clickBlock
{
    self = [self initWithTitle:title style:style target:self action:@selector(handleClick)];
    if (self) {
        objc_setAssociatedObject(self, barbuttonItemBlockKey, clickBlock, OBJC_ASSOCIATION_COPY);
    }
    return self;
}

- (void)handleClick
{
    void (^block)() = objc_getAssociatedObject(self, barbuttonItemBlockKey);
    if (block ) {
        block();
    }
}

@end

.m實現(xiàn)是將外界傳進來的clickBlock跟self進行關(guān)聯(lián)

 objc_setAssociatedObject(self, barbuttonItemBlockKey, clickBlock, 

當點擊Item對象的時候,執(zhí)行handClick方法,在handClick方法通過self拿到外界傳遞進來的Block,并執(zhí)行

 void (^block)() = objc_getAssociatedObject(self, barbuttonItemBlockKey);
    if (block ) {
        block();
}

下面使用我們經(jīng)常處理按鈕點擊的常用方法來使用objc_setAssociatedObject實現(xiàn)

1.創(chuàng)建一個UIButton的分類

#import <UIKit/UIKit.h>

@interface UIButton (Block)

- (void)addBlock:(void(^)())clickBlock;
@end

#import "UIButton+Block.h"
#import <objc/runtime.h>

const char *buttonBlockKey = "buttonBlockKey";

@implementation UIButton (Block)

- (void)addBlock:(void(^)())clickBlock
{
    [self addTarget:self action:@selector(handleClick) forControlEvents:UIControlEventTouchUpInside];
    objc_setAssociatedObject(self, buttonBlockKey, clickBlock, OBJC_ASSOCIATION_COPY);
    
    
}

- (void)handleClick
{
    void (^block)() = objc_getAssociatedObject(self, buttonBlockKey);
    if (block ) {
        block();
    }
}
@end

那么我們在代碼中監(jiān)聽按鈕的點擊事件

[btn addBlock:^{
// 當按鈕被點擊執(zhí)行的代碼
        NSLog(@"-------");
    }];