在保存UIViewController中將UILabel從一個位置影片到另一個位置

我有 2 個 UILabels：usernameLabel位于左上角fadingWelcomeMessageLabel，我向用戶顯示歡迎資訊。我想實作一個簡單的影片，自定義持續時間為幾秒鐘，這將最小化大小并淡入淡出（溶解）我fadingWelcomeMessageLabel從原始位置到usernameLabel位置。這怎么可能？下面是我想做的事情以及我當前的源代碼的螢屏截圖。提前致謝。

import UIKit

class ViewController: UIViewController {
    
    var fadingWelcomeMessageLabel: UILabel!
    var usernameLabel            : UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
        setupUsernameLabel()
        setupWelcomeMessageLabel()
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        
        UILabel.transition(with: usernameLabel, duration: 0.5, options: UIView.AnimationOptions.transitionCrossDissolve, animations: {
        }, completion: { (fininshed: Bool) -> () in
            self.fadeWelcomeMessage(message: "Hello, Mr User !", color: .orange, finalAlpha: 0.0)
        })
    }
    
    func setupUsernameLabel() {
        usernameLabel               = UILabel()
        usernameLabel.text          = "Mr User"
        usernameLabel.numberOfLines = 0
        view.addSubview(usernameLabel)
        
        usernameLabel.translatesAutoresizingMaskIntoConstraints = false
        usernameLabel.leftAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leftAnchor, constant: 10).isActive = true
        usernameLabel.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 0).isActive   = true
        usernameLabel.widthAnchor.constraint  (equalToConstant: 200).isActive                                   = true
        usernameLabel.heightAnchor.constraint (equalToConstant: 50).isActive                                    = true
    }

    func setupWelcomeMessageLabel() {
        // Fading Welcome Message Label
        fadingWelcomeMessageLabel               = UILabel()
        fadingWelcomeMessageLabel.text          = String()
        fadingWelcomeMessageLabel.numberOfLines = 0
        view.addSubview(fadingWelcomeMessageLabel)
        fadingWelcomeMessageLabel.isHidden      = true

        fadingWelcomeMessageLabel.translatesAutoresizingMaskIntoConstraints = false
        fadingWelcomeMessageLabel.centerXAnchor.constraint(equalTo: view.safeAreaLayoutGuide.centerXAnchor).isActive            = true
        fadingWelcomeMessageLabel.topAnchor.constraint    (equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 0).isActive   = true
        fadingWelcomeMessageLabel.widthAnchor.constraint  (equalTo: view.safeAreaLayoutGuide.widthAnchor).isActive              = true
        fadingWelcomeMessageLabel.heightAnchor.constraint (equalToConstant: 200).isActive                                       = true
    }
    
    func fadeWelcomeMessage(message: String, color: UIColor, finalAlpha: CGFloat) {
        fadingWelcomeMessageLabel.text                  = message
        fadingWelcomeMessageLabel.alpha                 = 1.0
        fadingWelcomeMessageLabel.isHidden              = false
        fadingWelcomeMessageLabel.textAlignment         = .center
        fadingWelcomeMessageLabel.backgroundColor       = color
        fadingWelcomeMessageLabel.layer.cornerRadius    = 5
        fadingWelcomeMessageLabel.layer.masksToBounds   = true
        fadingWelcomeMessageLabel.font                  = UIFont.systemFont(ofSize: 24.0)
        UIView.animate(withDuration: 6.0, animations: { () -> Void in
            self.fadingWelcomeMessageLabel.alpha = finalAlpha
        })
    }
}

uj5u.com熱心網友回復：

CGAffineTransform可以幫助您。您可以運行我的代碼并根據需要更改值。我只展示了fadingWelcomeMessageLabel。希望你能明白。

class ViewController: UIViewController {
    
    let fadingWelcomeMessageLabel = UILabel()
    let usernameLabel = UILabel()

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = .gray
        viewSetup()
    }

    override func viewDidAppear(_ animated: Bool) {
        DispatchQueue.main.asyncAfter(deadline: .now() 3, execute: {
            UIView.animate(withDuration: 1.5) {
                self.fadingWelcomeMessageLabel.transform = CGAffineTransform(translationX: -300, y: -2200).concatenating(CGAffineTransform(scaleX: 0.4, y: 0.2))
            }
        })
    }
    
    func viewSetup() {
        fadingWelcomeMessageLabel.frame = CGRect(x: 10, y: view.frame.height/2 - 50, width: view.frame.width - 20, height: 300)
        fadingWelcomeMessageLabel.text = "Welcome Mr. David"
        fadingWelcomeMessageLabel.textColor = .green
        fadingWelcomeMessageLabel.textAlignment = .center
        fadingWelcomeMessageLabel.backgroundColor = .red
        view.addSubview(fadingWelcomeMessageLabel)
    }
}

uj5u.com熱心網友回復：

我的問題的解決方案已通過影片閉包中的 1 行代碼解決：

   func fadeWelcomeMessage(message: String, color: UIColor, finalAlpha: CGFloat) {
        fadingWelcomeMessageLabel.text                  = message
        fadingWelcomeMessageLabel.alpha                 = 1.0
        fadingWelcomeMessageLabel.isHidden              = false
        fadingWelcomeMessageLabel.textAlignment         = .center
        fadingWelcomeMessageLabel.backgroundColor       = color
        fadingWelcomeMessageLabel.layer.cornerRadius    = 5
        fadingWelcomeMessageLabel.layer.masksToBounds   = true
        fadingWelcomeMessageLabel.font                  = UIFont.systemFont(ofSize: 24.0)
        UIView.animate(withDuration: 6.0, delay: 4.0,  animations: { () -> Void in
            self.fadingWelcomeMessageLabel.transform = CGAffineTransform(translationX: -180, y: -80).scaledBy(x: 0.20, y: 0.20)
            self.fadingWelcomeMessageLabel.alpha = finalAlpha
        }) { finish in
            self.setupWelcomeMessageLabel()
        }
    }

輸出：

標籤：迅速 uiview动画

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