extension UIView {
    var safeArea: SafeAreaLayoutGuideProvider {
        if #available(iOS 11.0, *) {
            return self.safeAreaLayoutGuide
        } else {
            return self
        }
    }
}

protocol SafeAreaLayoutGuideProvider {
    var leadingAnchor: NSLayoutXAxisAnchor { get }
    var trailingAnchor: NSLayoutXAxisAnchor { get }
    var leftAnchor: NSLayoutXAxisAnchor { get }
    var rightAnchor: NSLayoutXAxisAnchor { get }
    var topAnchor: NSLayoutYAxisAnchor { get }
    var bottomAnchor: NSLayoutYAxisAnchor { get }
    var widthAnchor: NSLayoutDimension { get }
    var heightAnchor: NSLayoutDimension { get }
    var centerXAnchor: NSLayoutXAxisAnchor { get }
    var centerYAnchor: NSLayoutYAxisAnchor { get }
}

extension UILayoutGuide : SafeAreaLayoutGuideProvider {}
extension UIView: SafeAreaLayoutGuideProvider {}