监听

通知的方法

发送通知

[NSNotificationCenter defaultCenter] postNotification:<#(nonnull NSNotification *)#>

[NSNotificationCenter defaultCenter] postNotificationName:<#(nonnull NSString *)#> object:<#(nullable id)#> userInfo:<#(nullable NSDictionary *)#>

[NSNotificationCenter defaultCenter] postNotificationName:<#(nonnull NSString *)#> object:<#(nullable id)#>

接收通知

[NSNotificationCenter defaultCenter] addObserverForName:<#(nullable NSString *)#> object:<#(nullable id)#> queue:<#(nullable NSOperationQueue *)#> usingBlock:<#^(NSNotification * _Nonnull note)block#>

[NSNotificationCenter defaultCenter] addObserver:<#(nonnull NSObject *)#> forKeyPath:<#(nonnull NSString *)#> options:<#(NSKeyValueObservingOptions)#> context:<#(nullable void *)#>

[NSNotificationCenter defaultCenter] addObserver:<#(nonnull id)#> selector:<#(nonnull SEL)#> name:<#(nullable NSString *)#> object:<#(nullable id)#>

注销通知

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

监听字典里的值

添加观察者

NSMutableDictionary *dic = [NSMutableDictionary new];

[dic addObserver:self forKeyPath:@"username" options:NSKeyValueObservingOptionNew context:nil];

[dic setObject:@"2132132" forKey:@"username"];

值改变后,调用的方法:

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    
    NSLog(@"%@",object);
}

注销观察者

-(void)dealloc{

[dic removeObserver:self forKeyPath:@"username"];
}

监听键盘

• UIKIT_EXTERN NSString *const UIKeyboardWillShowNotification;
• UIKIT_EXTERN NSString *const UIKeyboardDidShowNotification;
• UIKIT_EXTERN NSString *const UIKeyboardWillHideNotification;
• UIKIT_EXTERN NSString *const UIKeyboardDidHideNotification;

添加观察者

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardWillShowdEvent:) name:UIKeyboardWillShowNotification object:nil];

接收到通知,调用方法:

- (void)keyBoardWillShowdEvent:(NSNotification *)notification{
     NSLog(@"%@",notification.userInfo);
}

注销观察者

-(void)dealloc{

   [[NSNotificationCenter defaultCenter] removeObserver:self];
}