ViewController.swift

//
//  ViewController.swift
//  gradientView
//
//  Created by Dave Krawczyk on 8/23/16.
//  Copyright © 2016 Windy City Lab. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var bottomView: UIView!
    @IBOutlet weak var button: UIButton!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.bottomView.addGradientAnimation()
        self.button.addGradientAnimation()
    }


    

}

extension UIColor {
//    Green:   128  205  201
//    Purple:  161  115  204
    class func glanceGreen() -> UIColor {
        return UIColor(red: (128.0/255.0), green: (205.0/255.0), blue: (201.0/255.0), alpha: 1)
    }
    class func glancePurple() -> UIColor {
        return UIColor(red: (161.0/255.0), green: (115.0/255.0), blue: (204.0/255.0), alpha: 1)
    }
}

extension UIView {
    
    func addGradientAnimation() {
        
        let gradient = CAGradientLayer()
        gradient.frame = self.bounds
        gradient.colors = [UIColor.glanceGreen().cgColor, UIColor.glancePurple().cgColor]
        gradient.startPoint = CGPoint(x: 1, y: 0)
        gradient.endPoint = CGPoint(x: 0, y: 1)
        self.layer.insertSublayer(gradient, at: 0)

        let fromColors = gradient.colors
        let toColors = [UIColor.glancePurple().cgColor, UIColor.glanceGreen().cgColor]
        
        gradient.colors = toColors
        
        let animation = CABasicAnimation(keyPath: "colors")
        animation.fromValue = fromColors
        animation.toValue = toColors
        animation.duration = 10.00
        animation.isRemovedOnCompletion = true
        animation.fillMode = kCAFillModeForwards
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        animation.autoreverses = true
        animation.repeatCount = Float.infinity
        gradient.add(animation, forKey: "animateGradient")

    }
    
}