How do I update the screen before applicationDidBecomeActive?

I need to hide something on the screen when the user has activates the application by switching it to the foreground.

I have tried inserting my cod开发者_开发百科e within applicationDidBecomeActive or applicationWillEnterForeground and although it runs OK the old screen with the text I want to hide is displayed momentarily.

How can I hide the field before the screen is redrawn?

Thanks

iphaaw

I think the problem is, iOS will capture a screenshot from your app in the moment it goes to the background, so the animation will work in an instant.

The only way in my opinion to do this is to hide / cover your view in moment the app goes to the background.

Write some code in applicationWillResignActive: to 'hide' whatever you need to hide.

I faced a similar situation but, instead of hiding, I wanted to show a block code screen to grant access. Anyway I think that the solution also applies to your needs.

I often implement a custom base view controller in my iOS applications. So instead of dealing with applicationDidBecomeActive: or applicationWillResignActive: I setup this view controller to listen for the equivalent notifications:

@interface BaseViewController : UIViewController

- (void)prepareForGrantingAccessWithNotification:(NSNotification *)notification;

- (void)grantAccessWithNotification:(NSNotification *)notification;

@end


@implementation BaseViewController

- (void)viewWillAppear:(BOOL)animated {
  [super viewWillAppear:animated];

  [self addNotificationHandler:@selector(grantAccessWithNotification:)
               forNotification:UIApplicationDidBecomeActiveNotification];

  [self addNotificationHandler:@selector(prepareForGrantingAccessWithNotification:)
               forNotification:UIApplicationWillResignActiveNotification];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)prepareForGrantingAccessWithNotification:(NSNotification *)notification {
  // Hide your views here
  myCustomView.alpha = 0;

  // Or in my case, hide everything on the screen
  self.view.alpha = 0;
  self.navigationController.navigationBar.alpha = 0;
}

- (void)grantAccessWithNotification:(NSNotification *)notification {
  // This is only necessary in my case
  [self presentBlockCodeScreen];
  self.view.alpha = 1;
  self.navigationController.navigationBar.alpha = 1;
  ...
}

@end