Allow a navigation bar in a view controller to behave as though the view controller was wrapped in a navigation controller - i.e. the navigation bar colour matches the status bar colour

ViewController.swift

// MARK: UIBarPositioningDelegate
extension ViewController : UIBarPositioningDelegate {
    // see iOS: setting statusbar color without using UINavigationController
    // http://stackoverflow.com/questions/31103076/ios-setting-statusbar-color-without-using-uinavigationcontroller
    // (delegate set in the storyboard)
    // ensures the status bar colour is set to the same as the navigation bar background colour; matches
    // the behaviour of wrapping the ViewController in a NavigationController.
    func positionForBar(bar: UIBarPositioning) -> UIBarPosition {
        return .TopAttached
    }
}