Difference between autorotation in iOS 8 and prior versions

Question

This question arose when I was making programmatically-created view controller. This controller was supposed to support any interface orientation. And according to good practice I was creating subviews on -viewDidLoad and setting up their frames on -viewWillLayoutSubviews . Such approach is good, because -viewWillLayoutSubviews not only layout your subviews on the beginning but also handles interface rotations and other changes of view controller's view.

On iOS 8 everything was ok, but when i was running the app on iOS 6 and 7 layout was broken. I found out that the reason was that the layout was based on self.view.frame property. And if you try to print the frame on -viewWillLayoutSubviews on different iOS versions, you will get different results, when device is in landscape mode.

- (void)viewWillLayoutSubviews
{
    [super viewWillLayoutSubviews];
    NSLog(@"%@", NSStringFromCGRect(self.view.frame));
}

Output on iOS 8 (after turning device to landscape mode):

2014-10-07 17:35:11.028 BlaBlaApp[361:12587] {{0, 0}, {568, 320}}

Output on iOS 7 and 6 (same device orientation):

2014-10-07 17:35:11.028 BlaBlaApp[361:12587] {{0, 0}, {320, 568}}

On iOS 7 and 6 view frame doesn't change when device orientation changes. But it was obviously for me that visible area of the view changes! I decided to investigate how actually interface rotation works...

Answer 1

On iOS 7 and 6 view is rotated by changing its transform property ( frame is unchanged). On iOS 8, in turn, transform property of the view controller's view is always equal to CGAffineTransformIdentity and the frame changes depending on orientation.

I managed to solve my problem with one string of code (without macros and if statements):

CGRect actualFrame = CGRectApplyAffineTransform(self.view.frame, self.view.transform);

Subviews can be positioned according to actualFrame in the similar way on any iOS version.