Finds rotation difference between two interface orientations

RotationDifference.m

/**
 Finds rotation difference between two interface orientations.
 For example, difference between Portrait and PortraitUpsideDown is 2 (rotate by 180 degrees),
 defference between Portrait and LandscapeLeft is 1 (rotate by 90 degrees).

 @param source source interface orientation
 @param destination destination interface orientation
 @return rotation difference between orientations in range [0, 3].
 */
NSInteger rotationDifference(UIInterfaceOrientation source, UIInterfaceOrientation destination) {
    NSArray *matrix = @[
        @(UIInterfaceOrientationPortrait),
        @(UIInterfaceOrientationLandscapeLeft),
        @(UIInterfaceOrientationPortraitUpsideDown),
        @(UIInterfaceOrientationLandscapeRight),
    ];
    NSInteger sourceIndex = [matrix indexOfObject:@(source)];
    NSInteger destinationIndex = [matrix indexOfObject:@(destination)];
    if (sourceIndex == NSNotFound || destinationIndex == NSNotFound) {
        return 0;
    } else {
        return ABS(sourceIndex - destinationIndex);
    }
}