Method triggered by Change in orientation

Question

Is here a way to run a method when the iOS devices orientation changes?

I would like to change only some objects orientations on the screen, and not others.

What delegates do I use etc.

Cheers -A newbie

Answer 1

Depends when you want to react:

If before rotation, override from UIViewController:

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
 // do something before rotation
}

If you want to perform something after rotation:

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
 // do something after rotation
}

Reference:

http://developer.apple.com/library/ios/documentation/UIKit/Reference/UIViewController_Class/Reference/Reference.html#//apple_ref/occ/instm/UIViewController/willRotateToInterfaceOrientation:duration:

Answer 2

UIDevice posts UIDeviceOrientationDidChangeNotification

UIApplication posts UIApplicationWillChangeStatusBarOrientationNotification and UIApplicationDidChangeStatusBarOrientationNotification and has a related delegate callback for each.

UIViewController receives several orientation related calls triggered by the UIDevice notification if the view controller is part of the controller hierarchy managed by a window.

If you are already using a UIViewController, implement some of the orientation related methods, otherwise register for the UIDevice notifications. The most important UIViewController method is shouldAutorotateToInterfaceOrientation because if that return NO the others are not called.