Question

I have a specific function on an app that is intended to work on iPhone 4 and iPad. I don’t have an iPad yet (because Apple forgot my country), so I have to test it on simulator.

I have a method that needs to grab the contents of the main screen as a CGImageRef.

I have this method:

- (CGImageRef)takeScreenshot {
    UIWindow *theScreen = [[UIApplication sharedApplication].windows objectAtIndex:0];
    UIGraphicsBeginImageContext(theScreen.frame.size);
    [[theScreen layer] renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return screenshot.CGImage;
}

When I compile and test the iPhone version of my app for the iPhone, it works perfectly. But when I compile and test the iPad version on iPad simulator, it returns a black screen.

For it to work, I have to change the “objectAtIndex:0” to “objectAtIndex:1” on the second line.

Is there any logic for this or it is just a simulator bug? As far as I know, index 0 is always the main screen.

Is there any other way to capture the main screen content from another class?

thanks in advance.

Answer 1

Maybe use the keyWindow to get the correct window directly?

UIWindow *theScreen = [[UIApplication sharedApplication] keyWindow];

For the country problem – consider ordering one from another country. 😉