グラデーションしてくれるView

GradientView.swift

import Foundation

@IBDesignable
class GradientView: UIView {
    
    @IBInspectable
    var startColor: UIColor = .white {
        didSet {
            self.updateGradientColors()
        }
    }
    
    @IBInspectable
    var endColor: UIColor = .black {
        didSet {
            self.updateGradientColors()
        }
    }
    
    override public class var layerClass: Swift.AnyClass {
        get {
            return CAGradientLayer.self
        }
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        self.initialize()
        self.updateGradientColors()
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.initialize()
        self.updateGradientColors()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    private func initialize() {
        self.backgroundColor = .clear
    }
    
    
    private func updateGradientColors() {
        if let gradientLayer = self.layer as? CAGradientLayer {
            gradientLayer.colors = [self.startColor.cgColor, self.endColor.cgColor]
        }
    }
}