Just check if your window occupies the whole screen:
BOOL isRunningInFullScreen = CGRectEqualToRect([UIApplication sharedApplication].delegate.window.frame, [UIApplication sharedApplication].delegate.window.screen.bounds);
If this is false, then you’re running in a split view or a slide over.
Here is the code snipped which will automatically maintain this flag irrespective of rotation
-(void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection
{
// simply create a property of 'BOOL' type
isRunningInFullScreen = CGRectEqualToRect([UIApplication sharedApplication].delegate.window.frame, [UIApplication sharedApplication].delegate.window.screen.bounds);
}