CODEWITHSUNDEEP
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John Baum
John Baum

Reputation: 3331

Hiding the KeyWindow to cause a blank screenshot to be taken

I am trying to prevent the Apple implemmntation of taking a screenshot of the current screen contents when an app suspends into the background. I have found a piece of code that sort of works but it comes with a catch. What it does is that it clears the keywindow on the screen so when the snapshot is taken, it is of a blank screen. This is the code snippet for the functionality:

- (void)applicationWillResignActive:(UIApplication *)application
{
    [ UIApplication sharedApplication ].keyWindow.hidden = YES;
}

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    [ UIApplication sharedApplication ].keyWindow.hidden = YES;
}

The trouble with the above code is that when the app returns to the foreground, the view is gone as it has become hidden and i cannot unhide it with a simple 

[ UIApplication sharedApplication ].keyWindow.hidden = NO;

in the applicationWillEnterForeground method of the app delegate. Does anyone know of a way to regain back the hidden view once i have hidden it in the background methods? Right now it is a black screen as the view has been hidden. What exactly happens when you hide a keywindow before going to background and then coming back. is that keywindow you hid before no longer the keywindow? Can anyone point me in the correct direction?

Thanks

Upvotes: 3

Views: 1532

Answers (1)

Carl Veazey
Carl Veazey

Reputation: 18363

Just made a demo project and was able to reproduce your issue. Indeed, the keyWindow property of the application is nil when applicationWillEnterForeground: is called.

Many times, your application's delegate will have a reference to its window - this is usually the Xcode default template for many applications. I was able to resolve the issue by calling 

self.window.hidden = NO;

Instead of [UIApplication sharedApplication.keyWindow.hidden = NO;. Assuming that, like most of the templates, your application delegate has a window reference.

Another alternative that worked for me is to call [self.window makeKeyAndVisible];.

All this was done on the iOS 6 simulator.

Hope this helps!

Upvotes: 4

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