添加
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(test) name:@"test" object:nil];
删除
[[NSNotificationCenter defaultCenter] removeObserver:self name:@"test" object:nil];
在dealloc用以下方法无法删除 需要指定通知的名字
[[NSNotificationCenter defaultCenter] removeObserver:self];