使用具有约束持续时间的动画在 swift 中移动按钮并在此期间检测触摸

Question

我想将一个按钮从 A 点移动到 B 点。A 点：leadingConstraint = 120, topConstraint = 400。 B 点：leadingConstraint = 120, topConstraint = 200。为了我的游戏目的，我不能使用框架。我还希望能够在它移动时检测到它的触摸（我不知道该怎么做）。我有这段代码，我试图移动按钮（使用带持续时间的动画）但发生的事情是它从左上角（小尺寸）开始而不是从 A 点开始。然后它转到 B 点（正常尺寸）。这是代码：

@IBAction func Start(sender: UIButton) { 
    var topAnchorforButton: NSLayoutConstraint!
    let button = UIButton()
    button.setTitle("button", forState: .Normal)
    button.setTitleColor(UIColor.blackColor(), forState: .Normal)
    button.addTarget(self, action: "buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    self.view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false
    topAnchorforButton = button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 400)
    NSLayoutConstraint.activateConstraints([
    button.widthAnchor.constraintEqualToConstant(75),
    button.heightAnchor.constraintEqualToConstant(75),
    button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 120),
    topAnchorforButton
        ])
    [UIView.animateWithDuration(5.0, delay: 0.0, options: [.CurveLinear, .AllowUserInteraction], animations: {
    topAnchorforButton.constant = 200                         
    self.view.layoutIfNeeded()
        }, completion: nil)]    
   }
func buttonPressed(sender: UIButton) {
    print("hi")
}

请帮忙。我也不想使用 CADisplayLink。提前致谢...安东

Answer 1

你的问题有3个问题：

按钮必须从 A 点开始，而不是从左上角开始。
按钮必须是正常尺寸，不能是小尺寸。
按钮在移动时可以点击

对于 (1) 和 (2)，您必须移动代码以在 viewDidLoad() 内添加按钮，并且还需要为 button 和 topAnchorForButton.[=26 保留实例=]

首先，您为 button 和 topAnchorForButton 声明两个属性。

var button: UIButton!
var topAnchorForButton: NSLayoutConstraint!

接下来，添加按钮并设置其在 viewDidLoad() 中的位置。

override func viewDidLoad() {
    super.viewDidLoad()

    button = UIButton()
    button.setTitle("button", forState: .Normal)
    button.setTitleColor(UIColor.blackColor(), forState: .Normal)
    button.addTarget(self, action: "buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    self.view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false

    topAnchorForButton = button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 400)
    NSLayoutConstraint.activateConstraints([
        topAnchorForButton,
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 120),
    ])
}

func buttonPressed(sender: UIButton) {
    print("hi")
}

@IBAction func start(sender: AnyObject) {
    topAnchorForButton.constant = 200

    [UIView.animateWithDuration(5.0, delay: 0.0, options: [.CurveLinear, .AllowUserInteraction], animations: {
        self.view.layoutIfNeeded()
        }, completion: nil)]
}

对于(3)，要点击一个移动的按钮，你需要在button's .layer.presentationLayer property上做点击测试。

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    guard let touch = (touches as NSSet).anyObject() as? UITouch else {
        return
    }

    let touchLocation = touch.locationInView(self.view)
    if button.layer.presentationLayer()?.hitTest(touchLocation) != nil {
        self.buttonPressed(button)
    }
}

如果您想在每次按下开始按钮时都创建一个新按钮，请将要添加的代码放入 start: 方法中并设置其位置。您不再需要为 button 和 topAnchorForButton 保留实例。您可以使用标签来检索按钮。

@IBAction func start(sender: AnyObject) {
    // Remove the previous button
    if let previousButton = self.view.viewWithTag(100) as? UIButton {
        previousButton.removeFromSuperview()
    }

    let button = UIButton()
    button.tag = 100 // Set a tag so you can retrieve the button
    button.setTitle("button", forState: .Normal)
    button.setTitleColor(UIColor.blackColor(), forState: .Normal)
    button.addTarget(self, action: "buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    self.view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false

    let topAnchorForButton = button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 400)
    NSLayoutConstraint.activateConstraints([
        topAnchorForButton,
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 120),
        ])

    self.view.layoutIfNeeded()

    [UIView.animateWithDuration(5.0, delay: 0.0, options: [.CurveLinear, .AllowUserInteraction], animations: {
        topAnchorForButton.constant = 200
        self.view.layoutIfNeeded()
        }, completion: nil)]
}

更新 touchesBegan:withEvent event:

的代码

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    guard let touch = (touches as NSSet).anyObject() as? UITouch else {
        return
    }

    guard let button = self.view.viewWithTag(100) as? UIButton else {
        return
    }

    let touchLocation = touch.locationInView(self.view)
    if button.layer.presentationLayer()?.hitTest(touchLocation) != nil {
        self.buttonPressed(button)
    }
}

请注意，如果您不喜欢使用标签来检索按钮，您可以为按钮声明一个属性。

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