How to trigger a function when the iPhone is rotated 90 degrees?

Question

How do I detect the rotation of the iPhone for approximately 90 degrees? Additionally, I don't need/want the screen itself to rotate. I just want to call a function when the phone has been rotated. Thanks!

Answer 1

Your view controller will be sent:

  -(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration

Implement it to do something when the phone is being rotated

After the rotation is done, you get:

  - (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation

Here it is in the docs (see Handling View Rotations)

http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIViewController_Class/Reference/Reference.html

Answer 2

When you rotate the device, your view controller receives a didRotateFromInterfaceOrientation: message, with the old orientation. You can check the interfaceOrientation property to see the current rotation, and do something accordingly.

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation

Answer 3

You need to catch the events sent prior to ViewController rotation. Namely:

- (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration

and post rotation

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation