GradientView in Swift

GradientView.swift

import UIKit

@IBDesignable class GradientView: UIView {
  
  @IBInspectable var topColor: UIColor = UIColor.white
  @IBInspectable var bottomColor: UIColor = UIColor.red
  
  override class var layerClass: AnyClass {
    return CAGradientLayer.self
  }
  
  override var layer: CAGradientLayer {
    return super.layer as! CAGradientLayer
  }
  
  override func layoutSubviews() {
    layer.colors = [topColor.cgColor, bottomColor.cgColor]
  }
}