Object-c Associated Object

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  oc的关联的作用在我看来就是将两个对象关联起来，用的时候在取出来（我做的项目就是和UITableView里面的一个属性关联起来了）

举个栗子：

- (void)viewDidLoad {
    [super viewDidLoad];
    UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    button.frame = CGRectMake(100, 100, 100, 100);
    [button setTitle:@"关联测试" forState:UIControlStateNormal];
    [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
    [button addTarget:self action:@selector(buttonTap) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:button];
}

- (void)buttonTap{
    UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@""
                                                     message:@"How (are) you doing" delegate:self cancelButtonTitle:@"Not bad" otherButtonTitles:@"Fine", nil];
    void (^block)(NSInteger) = ^(NSInteger buttonIndex){
        if (buttonIndex == 0) {
            NSLog(@"buttonIndex:0");
        }else{
            NSLog(@"buttonIndex:1");
        }
    };
    objc_setAssociatedObject(alert, key, block, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    [alert show];
    
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
    void (^block)(NSInteger) = objc_getAssociatedObject(alertView, key);
    block(buttonIndex);
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    
}

@end

参考链接：http://nshipster.com/associated-objects/

                 http://kingscocoa.com/tutorials/associated-objects/

Object-c Associated Object

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原文地址：http://blog.csdn.net/rainshenji/article/details/47135329