創(chuàng)建一個(gè)測(cè)試的UIButton
#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(cè)試" forState:UIControlStateNormal]; [self.button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal]; self.button.layer.borderWidth = 1.0f; [self.view addSubview:self.button]; //注冊(cè)監(jiān)聽(tīng)button的enabled狀態(tài) [self.button addObserver:self forKeyPath:@"enabled" options:NSKeyValueObservingOptionNew context:@"test_button"]; // 3秒鐘后改變當(dāng)前button的enabled狀態(tài) dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0f * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ self.button.enabled = YES; });}
添加監(jiān)聽(tīng)觀察者
/** * 監(jiān)聽(tīng)按鈕狀態(tài)改變的方法 * * @param keyPath 按鈕改變的屬性 * @param object 按鈕 * @param change 改變后的數(shù)據(jù) * @param context 注冊(cè)監(jiān)聽(tīng)時(shí)context傳遞過(guò)來(lái)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屬性改變了%@",[change objectForKey:@"new"]); }}
log輸出
2015-06-30 11:48:32.001 監(jiān)聽(tīng)控件某個(gè)屬性的改變[34212:570638] self.button的enabled屬性改變了1
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