Detecting iOS UIDevice orientation

Question

I need to detect when the device is in portrait orientation so that I can fire off a special animation. But I do not want my view to autorotate.

How do I override a view autorotating when the device is rotated to portrait? My app only needs to display it's view in landscape but it seems I need to support portrait also if I want to be able to detect a rotation to portrait.

Answer 1

Try doing the following when the application loads or when your view loads:

[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications]; [[NSNotificationCenter defaultCenter]    addObserver:self selector:@selector(orientationChanged:)    name:UIDeviceOrientationDidChangeNotification    object:[UIDevice currentDevice]]; 

Then add the following method:

- (void) orientationChanged:(NSNotification *)note {    UIDevice * device = note.object;    switch(device.orientation)    {        case UIDeviceOrientationPortrait:        /* start special animation */        break;         case UIDeviceOrientationPortraitUpsideDown:        /* start special animation */        break;         default:        break;    }; } 

The above will allow you to register for orientation changes of the device without enabling the autorotate of your view.

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Note

In all cases in iOS, when you add an observor, also remove it at appropriate times (possibly, but not always, when the view appears/disappears). You can only have "pairs" of observe/unobserve code. If you do not do this the app will crash. Choosing where to observe/unobserve is beyond the scope of this QA. However you must have an "unobserve" to match the "observe" code above.