Making transparent background (Esp. for UItextField)

UIView+Extensions.swift

extension UIView {
    
    func makeTransparentView(withOpacity alphaValue: CGFloat, color: UIColor) {
        let backgroundView = UIView()
        self.superview?.insertSubview(backgroundView, belowSubview: self)
        self.backgroundColor = UIColor.clearColor()
        
        backgroundView.alpha = alphaValue
        backgroundView.backgroundColor = color
        backgroundView.layer.cornerRadius = self.layer.cornerRadius
        
        backgroundView.translatesAutoresizingMaskIntoConstraints = false

        let top = NSLayoutConstraint(item: backgroundView, attribute: .Top, relatedBy: .Equal, toItem: self, attribute: .Top, multiplier: 1, constant: 0)
        let right = NSLayoutConstraint(item: backgroundView, attribute: .Leading, relatedBy: .Equal, toItem: self, attribute: .Leading, multiplier: 1, constant: 0)
        let width = NSLayoutConstraint(item: backgroundView, attribute: .Width, relatedBy: .Equal, toItem: self, attribute: .Width, multiplier: 1, constant: 0)
        let height = NSLayoutConstraint(item: backgroundView, attribute: .Height, relatedBy: .Equal, toItem: self, attribute: .Height, multiplier: 1, constant: 0)
        
        NSLayoutConstraint.activateConstraints([top, right, width, height])
    }
    
}