Loading view like Facebook

loadableShimmer.swift

extension UIView {
    func animateLoading () {
        let gradient = CAGradientLayer()
        gradient.startPoint = CGPoint(x: 0, y: 0)
        gradient.endPoint = CGPoint(x: 1, y: 0)
        gradient.frame = CGRect(x: 0, y: 0, width: self.bounds.size.width*3, height: self.bounds.size.height)
        
        let lowerAlpha: CGFloat = 0.75
        let solid = UIColor(white: 1, alpha: 1).cgColor
       
        let clear = UIColor(white: 1, alpha: lowerAlpha).cgColor
        gradient.colors     = [ clear, clear, clear, solid, solid, solid,solid,clear,clear,clear]
        gradient.locations  = [ 0,     0.1,   0.2,  0.3,  0.4,   0.5, 0.6, 0.7, 0.8, 0.9 ,1 ]
        let theAnimation : CABasicAnimation = CABasicAnimation(keyPath: "transform.translation.x")
        theAnimation.duration = 1
        theAnimation.repeatCount = Float.infinity
        theAnimation.autoreverses = false
        theAnimation.isRemovedOnCompletion = false
        theAnimation.fillMode = kCAFillModeBoth
        theAnimation.fromValue = -self.frame.size.width * 2
        theAnimation.toValue =  0
        gradient.add(theAnimation, forKey: "loaderAnimation")
        
        self.layer.mask = gradient
    }
}