Detect if app is running in Slide Over or Split View mode in iOS 9

Just another way to repackage all of this

extension UIApplication {
    public var isSplitOrSlideOver: Bool {
        guard let w = self.delegate?.window, let window = w else { return false }
        return !window.frame.equalTo(window.screen.bounds)
    }
}

then you can just

• UIApplication.shared.isSplitOrSlideOver in Swift
• UIApplication.sharedApplication.isSplitOrSlideOver in Objective-C

Note that, in Swift, the window object is a double optional... WTF!

For iOS 13+ (note, I haven't tested the iOS 13 code myself yet)

extension UIApplication {

    public var isSplitOrSlideOver: Bool {
        guard let window = self.windows.filter({ $0.isKeyWindow }).first else { return false }
        return !(window.frame.width == window.screen.bounds.width)
    }
}

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);
}