Layer 渐变示例

import UIKit

class GradientLayerViewController: UIViewController {

    lazy var gradientLayer: CAGradientLayer = {
      
        return CAGradientLayer()
        
    }()
    
    
    override func viewDidLoad() {
        super.viewDidLoad()

        setupGradientLayer()
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        // 注意位置 viewDidLayoutSubviews
        gradientLayer.frame = view.bounds
    }

    
    
    func setupGradientLayer(){
        
        gradientLayer.colors = [UIColor.red.cgColor, UIColor.green.cgColor]
    
        gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.0)
        
        gradientLayer.endPoint = CGPoint(x: 1.0, y: 1.0)
        
        view.layer.addSublayer(gradientLayer)
    }

}