平滑旋转并用阴影改变UIView的大小

问题：如何平滑旋转并用阴影改变 UIView 的大小？

答案：

要实现平滑旋转并用阴影改变 UIView 的大小，您可以使用以下技术：

Core Animation（核心动画）：使用 CABasicAnimation 创建基本动画，对 UIView 的缩放、旋转和透明度进行操作。

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let container = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        container.backgroundColor = .blue

        let animation = CABasicAnimation(keyPath: "transform.rotation")
        animation.fromValue = 0.0
        animation.toValue = CGFloat.pi/4
        animation.duration = 1.0
        animation.repeatCount = 1
        animation.autoreverses = true
        animation.timingFunction = CAMediaTimingFunction(name: .easeInOutQuart)

        container.layer.add(animation, forKey: "rotationAnimation")

        let gradientLayer = CAGradientLayer(frame: container.bounds)
        gradientLayer.frame = container.bounds
        gradientLayer.colors = [UIColor.red.cgColor, UIColor.green.cgColor]
        gradientLayer.startPoint = CGPoint(x: 0, y: 0)
        gradientLayer.endPoint = CGPoint(x: 1, y: 1)
        container.layer.addSublayer(gradientLayer)

        UIView.animate(withDuration: 2, delay: 0, options: .curveEaseInOut, animations: {
            self.container.frame = CGRect(x: 0, y: 0, width: 200, height: 200)
            self.container.layer.cornerRadius = 10
        }, completion: nil)
    }
}

CAGradientLayer（CAGradient图层）：使用 CAGradientLayer 添加渐变效果。

let gradientLayer = CAGradientLayer(frame: container.bounds)
gradientLayer.frame = container.bounds
gradientLayer.colors = [UIColor.red.cgColor, UIColor.green.cgColor]
gradientLayer.startPoint = CGPoint(x: 0, y: 0)
gradientLayer.endPoint = CGPoint(x: 1, y: 1)
container.layer.addSublayer(gradientLayer)

UIView动画：使用 UIView 的 animate 方法实现动画效果。

UIView.animate(withDuration: 2, delay: 0, options: .curveEaseInOut, animations: {
    self.container.frame = CGRect(x: 0, y: 0, width: 200, height: 200)
    self.container.layer.cornerRadius = 10
}, completion: nil)

以上三种方法都可以实现平滑旋转并阴影改变 UIView 的大小。可以根据您的需求选择最适合的方法。