Question

Is there a delegate that will get called when the iPhone enters landscape or portrait mode? I need to change the style and place objects in a different place when the iPhone get’s rotated. Do I have to do this with the accelerometer? Moreover if there exist such a delegate do I have to create the connection in interface builder. I am new to objective-c…

Answer 1

Register to listen for the orientation change notification.

UIDevice *device = [UIDevice currentDevice];
    //Tell it to start monitoring the accelerometer for orientation             
[device beginGeneratingDeviceOrientationNotifications];
    //Get the notification centre for the app   
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];    
[nc addObserver:self selector:@selector(orientationChanged:)        name:UIDeviceOrientationDidChangeNotification
         object:device];

Implement orientationChanged: method, which will be called when the device change the orientation. you could put code to check the orientation type and called your method.

- (void)orientationChanged:(NSNotification *)note
{
    NSLog(@"Orientation  has changed: %d", [[note object] orientation]);
}

Remove notification in dealloc.

[[NSNotificationCenter defaultCenter] removeObserver:self];
[[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];

Check the blog post

Reacting to iPhone’s orientation