柚子快报邀请码778899分享：KVO(1)

柚子快报邀请码778899分享：KVO(1)

http://yzkb.51969.com/

#import "ViewController.h"

@interface ViewController ()

@property(nonatomic, strong)UIButton *button;

@end

@implementation ViewController

- (void)viewDidLoad {

[super viewDidLoad];

self.button = [[UIButton alloc] initWithFrame:CGRectMake(30, 50, 50, 30)];

[self.button setTitle:@"測试" forState:UIControlStateNormal];

[self.button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];

self.button.layer.borderWidth = 1.0f;

[self.view addSubview:self.button];

//注冊监听button的enabled状态

[self.button addObserver:self forKeyPath:@"enabled" options:NSKeyValueObservingOptionNew context:@"test_button"];

// 3秒钟后改变当前button的enabled状态

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0f * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

self.button.enabled = YES;

});

// Do any additional setup after loading the view, typically from a nib.

}

/**

* 监听按钮状态改变的方法

*

* @param keyPath 按钮改变的属性

* @param object 按钮

* @param change 改变后的数据

* @param context 注冊监听时context传递过来的值

*/

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

UIButton *button = (UIButton *)object;

if (self.button == button && [@"enabled" isEqualToString:keyPath]) {

NSLog(@"self.button的enabled属性改变了%@",[change objectForKey:@"new"]);

}

}

柚子快报邀请码778899分享：KVO(1)

http://yzkb.51969.com/

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