UIView Extension

extension UIView {
    var leftAnchor: NSLayoutXAxisAnchor {
        return iOS11NAbove ? safeAreaLayoutGuide.leftAnchor : self.leftAnchor
    }
    
    var rightAnchor: NSLayoutXAxisAnchor {
        return iOS11NAbove ? safeAreaLayoutGuide.rightAnchor : self.rightAnchor
    }
    var topAnchor: NSLayoutYAxisAnchor {
        return iOS11NAbove ? safeAreaLayoutGuide.topAnchor : self.topAnchor
    }
    var bottomAnchor: NSLayoutYAxisAnchor {
        return iOS11NAbove ? safeAreaLayoutGuide.bottomAnchor : self.bottomAnchor
    }
    
    private var iOS11NAbove: Bool {
        if #available(iOS 11.0, *) {
            return true
        }
        return false
    }
}