Swift - CALayer

import UIKit
class ViewController: UIViewController{
    override func viewDidLoad() {
        super.viewDidLoad()
        let view = UIView(frame: CGRect(x: 150, y: 250, width: 100, height: 100))
        view.backgroundColor = UIColor.blue
        //CALayer邊框
        view.layer.borderWidth = 2
        view.layer.borderColor = UIColor.black.cgColor
        //CALayer陰影
        view.layer.shadowColor = UIColor.gray.cgColor
        view.layer.shadowOffset = CGSize(width: 10, height: 10)
        view.layer.shadowOpacity = 0.5
        view.layer.shadowRadius = 5.0
        //CGLayer圓角
        view.layer.masksToBounds = true//設置圓角半徑對view有用，但對view的內容不起做用，因此對內容進行裁邊
        view.layer.cornerRadius = 100
        self.view.addSubview(view)
        //CALayer漸變
        let view2 = UIView(frame: CGRect(x: 150, y: 400, width: 100, height: 100))
        let gradientLayer = CAGradientLayer()
        gradientLayer.frame = view2.bounds
        let formColor = UIColor.yellow.cgColor
        let midColor = UIColor.blue.cgColor
        let toColor = UIColor.red.cgColor
        gradientLayer.colors = [formColor,midColor,toColor]
        view2.layer.addSublayer(gradientLayer)
        //設置漸變方向
        gradientLayer.startPoint = CGPoint(x: 0, y: 0)//值在0～1
        gradientLayer.endPoint = CGPoint(x: 1, y: 1)
        //設置漸變行走軌跡
        gradientLayer.locations = [0,0.5,1]
        
        self.view.addSubview(view2)
    }
    
}