在约束布局中创建视图并为其设置动画

import UIKit

class ViewController: UIViewController {
    var myView: UIView!
    var leadingConstraint: NSLayoutConstraint!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建视图
        myView = UIView()
        myView.backgroundColor = .red
        myView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(myView)
        
        // 添加约束
        leadingConstraint = myView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20)
        leadingConstraint.isActive = true
        myView.topAnchor.constraint(equalTo: view.topAnchor, constant: 100).isActive = true
        myView.widthAnchor.constraint(equalToConstant: 100).isActive = true
        myView.heightAnchor.constraint(equalToConstant: 100).isActive = true
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        // 设置动画
        UIView.animate(withDuration: 1.0, animations: {
            self.leadingConstraint.constant = 200
            self.view.layoutIfNeeded()
        })
    }
}