Question

I use following code I found in the web to rotate the screen to landscape mode. I don’t understand what they suppose to do. Specially the bounds it is setting. Can someone give some explanation what it is doing?

if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortrait)
{
    CGRect statusBarFrame = [[UIApplication sharedApplication] statusBarFrame];

    [[UIApplication sharedApplication] setStatusBarOrientation:UIInterfaceOrientationLandscapeRight animated:NO];


    UIScreen *screen = [UIScreen mainScreen];
    CGRect newBounds = CGRectMake(0, 0, screen.bounds.size.height, screen.bounds.size.width - statusBarFrame.size.height);



    self.navigationController.view.bounds = newBounds;
    self.navigationController.view.center = CGPointMake(newBounds.size.height / 2.0, newBounds.size.width / 2.0);
    self.navigationController.view.transform = CGAffineTransformConcat(self.navigationController.view.transform, CGAffineTransformMakeRotation(degreesToRadian(90)));
    self.navigationController.view.center = window.center;
}

Answer 1

Your rootView’s size used to be (320, 480) for example, after rotating, you should set it to (480, 320) in order to fit the screen in landscape mode, that’s why you need to change the bounds of your view.

Set the transform is making the view actually rotate 90 degrees.

UIKit is doing the similar things when automatically rotate for you.