简单的平移、缩放和旋转以及渐隐渐显，都可以使用

UIView.animate(withDuration: 0.25, animations: {            // 最终的结果显示        }) { (_) in            // 动画完成之后要进行的操作        }

如果是稍微复杂的动画，比如沿着曲线运动，就可以考虑使用关键帧动画CAKeyframeAnimation实现。

效果图1：

动画1.gif

效果图2:

动画2.gif

效果1代码：

////  ViewController.swift//  关键帧动画CAKeyframeAnimation////  Created by iOS on 2018/5/22.//  Copyright © 2018年 weiman. All rights reserved.//import UIKitclass ViewController: UIViewController {    @IBOutlet weak var redView: UIView!    @IBOutlet weak var purpleView: UIView!        override func viewDidLoad() {        super.viewDidLoad()                redView.layer.cornerRadius = redView.frame.size.width/2.0        redView.layer.masksToBounds = true        purpleView.layer.cornerRadius = purpleView.frame.size.width/2.0        purpleView.layer.masksToBounds = true                animationOne()        animationTwo()    }       //一个数组，提供了一组关键帧的值， 当使用path的 时候 values的值自动被忽略。    func animationOne() {        /*         提供一组关键帧位置，使得动画view的中心依次落在这些关键点上，形成动画         */        let animation = CAKeyframeAnimation(keyPath: "position")        let value1: NSValue = NSValue(cgPoint: CGPoint(x: 100, y: 100))        let value2: NSValue = NSValue(cgPoint: CGPoint(x: 200, y: 100))        let value3: NSValue = NSValue(cgPoint: CGPoint(x: 200, y: 200))        let value4: NSValue = NSValue(cgPoint: CGPoint(x: 100, y: 200))        let value5: NSValue = NSValue(cgPoint: CGPoint(x: 100, y: 300))        let value6: NSValue = NSValue(cgPoint: CGPoint(x: 200, y: 400))        animation.values = [value1, value2, value3, value4, value5, value6]                animation.repeatCount = MAXFLOAT        animation.autoreverses = true        animation.duration = 4.0        animation.isRemovedOnCompletion = false        animation.fillMode = kCAFillModeForwards        animation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)]        animation.delegate = self                redView.layer.add(animation, forKey: nil)    }        func animationTwo() {                let screenWidth = UIScreen.main.bounds.size.width        let screenHeight = UIScreen.main.bounds.size.height                let animation = CAKeyframeAnimation(keyPath: "position")        let value1 = NSValue(cgPoint: CGPoint(x: screenWidth/2.0, y: 0))        let value2 = NSValue(cgPoint: CGPoint(x: screenWidth, y: 100))        let value3 = NSValue(cgPoint: CGPoint(x: 0, y: screenHeight/2.0))        let value4 = NSValue(cgPoint: CGPoint(x: screenWidth/2.0, y: screenHeight))        animation.values = [value1,value2,value3,value4,value1]        animation.repeatCount = MAXFLOAT        animation.autoreverses = true        animation.duration = 6.0        animation.isRemovedOnCompletion = false        animation.fillMode = kCAFillModeForwards        animation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)]        animation.delegate = self                purpleView.layer.add(animation, forKey: nil)    }}extension ViewController: CAAnimationDelegate {        }

效果2代码：

////  SecondViewController.swift//  关键帧动画CAKeyframeAnimation////  Created by iOS on 2018/5/22.//  Copyright © 2018年 weiman. All rights reserved.//import UIKitclass SecondViewController: UIViewController {    @IBOutlet weak var blueView: UIView!    @IBOutlet weak var greenView: UIView!    @IBOutlet weak var yellowView: UIView!        let screenWidth = UIScreen.main.bounds.size.width    let screenHeight = UIScreen.main.bounds.size.height        override func viewDidLoad() {        super.viewDidLoad()        blueView.layer.cornerRadius = blueView.frame.size.width/2.0        blueView.layer.masksToBounds = true        greenView.layer.cornerRadius = greenView.frame.size.width/2.0        greenView.layer.masksToBounds = true        yellowView.layer.cornerRadius = yellowView.frame.size.width/2.0        yellowView.layer.masksToBounds = true        animationPathBlue()        animationGreen()        animationYellow()            }    @IBAction func back(_ sender: UIButton) {        dismiss(animated: true, completion: nil)    }        /// 使用path的方式实现动画    /*     这是一个 CGPathRef 对象，默认是空的，当我们创建好CAKeyframeAnimation的实例的时候，可以通过制定一个自己定义的path来让 某一个物体按照这个路径进行动画。这个值默认是nil 当其被设定的时候 values 这个属性就被覆盖     */        /// 沿着圆周运动    func animationPathBlue() {                // 创建动画对象        let animation = CAKeyframeAnimation(keyPath: "position")        // 创建一个CGPathRef对象，就是动画的路线        let path = CGMutablePath()        //  自动沿着弧度移动        path.addEllipse(in: CGRect(x: 0, y: 50, width: screenWidth, height: 100))                animation.path = path        animation.autoreverses = true        animation.repeatCount = MAXFLOAT        animation.isRemovedOnCompletion = false        animation.fillMode = kCAFillModeForwards        animation.duration = 3.0        animation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)]        animation.delegate = self                blueView.layer.add(animation, forKey: nil)    }        /// 沿着直线运动    func animationGreen() {        // 创建动画对象        let animation = CAKeyframeAnimation(keyPath: "position")        // 创建一个CGPathRef对象，就是动画的路线        let path = CGMutablePath()        // 设置开始位置        path.move(to: CGPoint(x: 0, y: 150))        // 沿着直线移动        /*         Z字轨迹         */        path.addLine(to: CGPoint(x: screenWidth, y: 150))        path.addLine(to: CGPoint(x: 0, y: 200))        path.addLine(to: CGPoint(x: screenWidth, y: 200))        path.addLine(to: CGPoint(x: 0, y: 200))        path.addLine(to: CGPoint(x: screenWidth, y: 150))                animation.path = path        animation.autoreverses = true        animation.repeatCount = MAXFLOAT        animation.isRemovedOnCompletion = false        animation.fillMode = kCAFillModeForwards        animation.duration = 6.0        animation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)]        animation.delegate = self                greenView.layer.add(animation, forKey: nil)    }        /// 曲线运动    func animationYellow() {        // 创建动画对象        let animation = CAKeyframeAnimation(keyPath: "position")        // 创建一个CGPathRef对象，就是动画的路线        let path = CGMutablePath()        // 设置开始位置        path.move(to: CGPoint(x: 0, y: screenHeight))        // 沿着曲线移动        path.addCurve(to:       CGPoint(x: screenWidth, y: screenHeight/2.0),                      control1: CGPoint(x: screenWidth/4.0, y: screenHeight/4.0),                      control2: CGPoint(x: screenWidth/2.0, y: screenHeight/2.0))        //        path.addCurve(to:       CGPoint(x: 150.0, y: 275.0),//                      control1: CGPoint(x: 250.0, y: 275.0),//                      control2: CGPoint(x: 90.0, y: 120.0))////        path.addCurve(to:       CGPoint(x: 250.0, y: 275.0),//                      control1: CGPoint(x: 350.0, y: 275.0),//                      control2: CGPoint(x: 110.0, y: 120.0))////        path.addCurve(to:       CGPoint(x: 350.0, y: 275.0),//                      control1: CGPoint(x: 450.0, y: 275.0),//                      control2: CGPoint(x: 130.0, y: 120.0))                animation.path = path        animation.autoreverses = true        animation.repeatCount = MAXFLOAT        animation.isRemovedOnCompletion = false        animation.fillMode = kCAFillModeForwards        animation.duration = 3.0        animation.timingFunctions = [CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)]        animation.delegate = self                yellowView.layer.add(animation, forKey: nil)            }}extension SecondViewController: CAAnimationDelegate {    }

demo地址：