ios - ApplicationDidLaunch 中的 RemoveFromSuperView UIImageView 延迟执行

Question

我创建了一个 UIImageView，然后在 ApplicationDidLaunch 中为它分配了一个模糊的背景图像。这个 imageview 覆盖了整个屏幕，注定要覆盖底层的 View Controller

UIImage *captureImage = [self captureView:tabBar.view];
backgroundImage.image = [captureImage applyExtraLightEffect];
backgroundImage.frame = [[UIScreen mainScreen] applicationFrame];

[tabBar.view addSubview:backgroundImage];

然后我要求显示很好的触摸 ID。如果 TouchID 身份验证成功，我想用漂亮的淡出动画删除背景图像

[context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics
        localizedReason:@"Are you the device owner?"
                  reply:^(BOOL success, NSError *error) {
                      if (error) {
                          UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
                                                                          message:@"There was a problem verifying your identity."
                                                                         delegate:nil
                                                                cancelButtonTitle:@"Ok"
                                                                otherButtonTitles:nil];
                          [alert show];
                          exit(0);
                          return;
                      }
                      if (success) {
                          NSLog(@"Passcode via TOUCH ID entered OK");

                          [UIView animateWithDuration:0.5
                                           animations:^{backgroundImage.alpha = 0;}
                                           completion:^(BOOL finished){[[tabBar.view viewWithTag:13] removeFromSuperview];; }];
                          // [UIView setAnimationDidStopSelector:@selector(startupAnimationDone:finished:context:)];
                          [UIView setAnimationDelegate:self];
                      }

现在我的问题是代码会立即执行，但是删除 backgroundImage 框架需要 5-10 秒才能执行。它发生在我所有的 iDevices 上。我不明白为什么在删除 super View 之前会有延迟。有人知道吗？

Answer 1

完成 block 可能没有在主线程上返回。如果是这种情况，那么如果您尝试更改它们， View 将以意想不到的方式运行。尝试将所有 View 操作代码放入 dispatch_async(dispatch_get_main_queue()) block 中。