多次添加观察者addObserver 多次添加观察者addObserver

确保添加一次观察者

- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib.[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] removeObserver:self name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] removeObserver:self name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] removeObserver:self name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; }- (IBAction)btnClick:(id)sender {[[NSNotificationCenter defaultCenter] postNotificationName:kCESHITONGZHI object:nil userInfo:nil]; }-(void)showMSG{ NSLog(@"I'm here"); }

执行结果：
测试重复通知[7866:2161604] I'm here
多次添加观察者

- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib.- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib.[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(showMSG) name:kCESHITONGZHI object:nil]; }- (IBAction)btnClick:(id)sender {[[NSNotificationCenter defaultCenter] postNotificationName:kCESHITONGZHI object:nil userInfo:nil]; }-(void)showMSG{ NSLog(@"I'm here"); }}- (IBAction)btnClick:(id)sender {[[NSNotificationCenter defaultCenter] postNotificationName:kCESHITONGZHI object:nil userInfo:nil]; }-(void)showMSG{ NSLog(@"I'm here"); }

【多次添加观察者addObserver】执行结果：
测试重复通知[7869:2162423] I'm here
测试重复通知[7869:2162423] I'm here
测试重复通知[7869:2162423] I'm here
测试重复通知[7869:2162423] I'm here