Question

我正在向窗口添加UIView，同时发生一些线程后台更新，然后使用委托方法删除视图。一切都按预期发生，但在调用hideActivityViewer后，视图仍会持续几秒钟。不确定是否重要，但应用程序使用UITabBarController。

更新方法位于一个单独的类中，但目前在AppDelegate.m中用于调试目的。正如我所说，一切正常。更新完成后，它会将“Foo”写入日志，但视图会持续几秒钟。任何帮助，将不胜感激。多余的代码已被省略：

AppDelegate.h

@interface AppDelegate : NSObject <UIApplicationDelegate, UITabBarControllerDelegate> {
  UIWindow *window;
  UITabBarController *tabBarController;
  UIView *activityView;
  id _delegate;
}
@property (nonatomic, retain) IBOutlet UIWindow *window;
@property (nonatomic, retain) UITabBarController *tabBarController;
- (void)showActivityViewer;
- (void)updateComplete;
- (void)updateRemoteDataThreadedWithDelegate:(id)aDelegate;
- (id)delegate;
- (void)setDelegate:(id)new_delegate;
@end

AppDelegate.m

- (void)updateRemoteDataThreadedWithDelegate:(id)aDelegate {
  [self setDelegate:aDelegate];
  NSOperationQueue *queue = [NSOperationQueue new];
  NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(updateRemoteDataWithDelegate:) object:aDelegate];
  [queue addOperation:operation];
  [operation release];
}

- (void)updateRemoteDataWithDelegate:(id)aDelegate {
  [self setDelegate:aDelegate];
  ...do stuff...
  if ([_delegate respondsToSelector:@selector(updateComplete)]) {
    [_delegate updateComplete];
  } else { 
    [NSException raise:NSInternalInconsistencyException format:@"Delegate doesn't respond to updateComplete"];
  }
}

-(void)showActivityViewer {
  [activityView release];
  activityView = [[UIView alloc] initWithFrame: CGRectMake(window.bounds.size.width-50, 60, 50, 50)];
  ...formatting...
  [window addSubview: activityView];
  [activityView release];
}
-(void)hideActivityViewer {
  [activityView removeFromSuperview];
  activityView = nil;
  NSLog(@"Foo");
}

- (id)delegate {
  return _delegate;
}

- (void)setDelegate:(id)new_delegate {
  _delegate = new_delegate;
}

Answer 1

在我看来，你正在使一个线程调用一个在UIView中执行操作的委托方法 - 你不能这样做，因为UIView不是线程安全的。

使用performSelectorOnMainThread安全地执行此操作 - 您的委托方法可以通过这种方式调用主线程上的另一个方法。

Answer 2

UI操作应该在主线程上完成;你的例子将UIView推送到一个单独的线程，不建议这样做。

UIView从superview中删除很慢

2 个答案: