我有下一个代码:
@implementation SplashViewVC
- (void)viewDidLoad
{
[super viewDidLoad];
self.splashView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"Default.png"]];
self.activityIndicator.originY = 355.f;
[[NSNotificationCenter defaultCenter] addObserverForName:NCDownloadComplete object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *n){
NSInteger errorCode = [n.userInfo[@"errorCode"] integerValue];
[self.activityIndicator stopAnimating];
if (errorCode == ERROR_CODE_NO_CONNECTION) {
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Some problem with server" delegate:self cancelButtonTitle:@"try again" otherButtonTitles:nil];
[alertView show];
} else if (errorCode == 0) {
[self dismissViewControllerAnimated:YES completion:nil];
}
}];
[self downloadData];
}
- (void)downloadData
{
[self.activityIndicator startAnimating];
[[Server sharedServer] getMovieData];
}
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
[self downloadData];
}
- (void)viewDidDisappear:(BOOL)animated
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
[super viewDidDisappear:animated];
}
@end
所以我在开始处放置了断点viewDidLoad
方法,在viewDidDisappear
。当我启动首先转到的应用程序时viewDidload
,下载后进入viewDidDisappear
.
但在我的应用程序中,我再次下载数据并发布notification: NSDownloadComplete
。在这个 VC 中它可以工作,但我后来使用以下方法删除了:
[[NSNotificationCenter defaultCenter] removeObserver:self]
这个VC使用viewDidLoad
一旦开始,就不能再添加Observer。
怎么了?
EDIT我尝试将 addObserver 方法添加到viewWillAppear
or viewWillDisappear
- 没有结果。
我加NSLog(@"addObserver");
before
[[NSNotificationCenter defaultCenter] addObserverForName...
在 viewDidLoad 中
和写
- (void)viewDidDisappear:(BOOL)animated
{
NSLog(@"removeObserver");
[[NSNotificationCenter defaultCenter] removeObserver:self];
[super viewDidDisappear:animated];
}
在日志中我看到:
2013-06-10 14:32:05.646 myApp[9390:c07] addObserver
2013-06-10 14:32:06.780 myApp[9390:c07] removeObserver
怎么了?
EDIT 2您可以看到观察者必须被删除,但它再次在 addObserver 方法中运行块