UIView和UILabels在iPhone上的渐变

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // 创建一个渐变层
        let gradientLayer = CAGradientLayer()
        gradientLayer.frame = view.bounds

        // 设置渐变颜色
        gradientLayer.colors = [UIColor.red.cgColor, UIColor.blue.cgColor]

        // 添加渐变层到视图上
        view.layer.addSublayer(gradientLayer)

        // 创建一个UILabel
        let label = UILabel(frame: CGRect(x: 50, y: 100, width: 200, height: 50))
        label.text = "Hello, World!"
        label.textColor = .white

        // 为UILabel添加渐变层
        let labelGradientLayer = CAGradientLayer()
        labelGradientLayer.frame = label.bounds
        labelGradientLayer.colors = [UIColor.red.cgColor, UIColor.blue.cgColor]
        label.layer.addSublayer(labelGradientLayer)

        // 将UILabel添加到视图上
        view.addSubview(label)
    }
}