Ios 如何更改以编程方式创建的按钮的约束？

我想使用编程创建的约束将编程创建的按钮移动到该按钮。但是我遇到了几个错误。我可以对一个按钮执行此操作，该按钮是非编程创建的，约束也是非编程创建的。代码如下：

var displayLink: CADisplayLink?
var startTime: CFAbsoluteTime?
let duration = 2.0
@IBOutlet var TopConstraintforMoving1: NSLayoutConstraint!  
@IBAction func Startbutton(sender: UIButton) {
    startDisplayLink()
}
func startDisplayLink() {
    displayLink?.invalidate()
    startTime = CFAbsoluteTimeGetCurrent()
    displayLink = CADisplayLink(target: self, selector: "handleDisplayLink:")
    displayLink?.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes)
func handleDisplayLink(displayLink: CADisplayLink) {
    let elapsed = CFAbsoluteTimeGetCurrent() - startTime!
    var percentComplete = CGFloat(elapsed / duration)
    if percentComplete >= 1.0 {
        percentComplete = 1.0
        stopDisplayLink()
    }
    TopConstraintforMoving1.constant = 390 - 350 * percentComplete
}

let button = UIButton()
var displayLink: CADisplayLink?
var startTime: CFAbsoluteTime?
let duration = 2.0
var topConstraint: NSLayoutConstraint!
@IBAction func start(sender: UIButton) {
    displayLink?.invalidate()
    startTime = CFAbsoluteTimeGetCurrent()
    displayLink = CADisplayLink(target: self, selector: "handleDisplayLink:")
    displayLink?.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes)
}
func handleDisplayLink(displayLink: CADisplayLink) {
    button.hidden = false
    let elapsed = CFAbsoluteTimeGetCurrent() - startTime!
    var percentComplete = CGFloat(elapsed / duration)
    if percentComplete >= 1.0 {
        percentComplete = 1.0
        displayLink.invalidate()
        button.hidden = true
    }
    topConstraint.constant = 393 - 350 * percentComplete
    NSLayoutConstraint.activateConstraints([
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 122),
        topConstraint,
        button.widthAnchor.constraintEqualToConstant(75),
        button.heightAnchor.constraintEqualToConstant(75)
        ])
}
func buttonPressed(sender: UIButton!) {
    button.hidden = true
    displayLink?.invalidate()
}
override func viewDidLoad() {
    super.viewDidLoad()
    button.hidden = true
    button.setImage(UIImage(named: "BlueBall.png")!, forState: UIControlState.Normal)
    button.addTarget(self, action: "buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    self.view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false
    topConstraint = button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 393)  
    NSLayoutConstraint.activateConstraints([
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 122),
        topConstraint,
        button.widthAnchor.constraintEqualToConstant(75),
        button.heightAnchor.constraintEqualToConstant(75)
        ])   
}

这是我用编程方式创建的按钮的代码：

var startTime: CFAbsoluteTime?
let duration = 2.0
let button = UIButton(type: UIButtonType.System) as UIButton
var topConstraintforMoving1: NSLayoutConstraint?  
@IBAction func StartButton(sender: UIButton) {
    startTime = CFAbsoluteTimeGetCurrent()
    let elapsed = CFAbsoluteTimeGetCurrent() - startTime!
    var percentComplete = CGFloat(elapsed / duration)
    if percentComplete >= 1.0 {
        percentComplete = 1.0
    }
    button.setImage(UIImage(named: "BlueBall.png")!, forState: UIControlState.Normal)
    button.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
    view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false      
    topConstraintforMoving1 = button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 390 - 350 * percentComplete)  
    NSLayoutConstraint.activateConstraints([
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 122),
        button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 393),
        button.widthAnchor.constraintEqualToConstant(75),
        button.heightAnchor.constraintEqualToConstant(75),
        ])      
} 

按钮不动了。

---

请帮忙，谢谢。安东

你在正确的轨道上。在代码中创建按钮的代码中，也在代码中创建约束。但是，您没有保存指向该约束的指针

（函数

constraintEqualToAnchor

的返回类型为NSLayoutConstraint，但您不会将该返回值保存在任何位置。）

创建实例变量并将约束保存到该变量。如果愿意，甚至可以将约束标记为IBOutlet

然后像处理在IB（Interface Builder）中创建的按钮一样，操纵约束的常量值

编辑： 您的代码可能如下所示：

TopConstraintforMoving1 = 
  button.topAnchor.constraintEqualToAnchor(
    view.topAnchor, 
    constant: 390 - 350 * percentComplete)

请注意，变量名应该以小写字母开头，因此实际上应该是：

topConstraintforMoving1 = 
  button.topAnchor.constraintEqualToAnchor(
    view.topAnchor, 
    constant: 390 - 350 * percentComplete)

---

我尝试以不同的方式构建它，但使用了相同的方法，它成功了。代码如下：

var displayLink: CADisplayLink?
var startTime: CFAbsoluteTime?
let duration = 2.0
@IBOutlet var TopConstraintforMoving1: NSLayoutConstraint!  
@IBAction func Startbutton(sender: UIButton) {
    startDisplayLink()
}
func startDisplayLink() {
    displayLink?.invalidate()
    startTime = CFAbsoluteTimeGetCurrent()
    displayLink = CADisplayLink(target: self, selector: "handleDisplayLink:")
    displayLink?.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes)
func handleDisplayLink(displayLink: CADisplayLink) {
    let elapsed = CFAbsoluteTimeGetCurrent() - startTime!
    var percentComplete = CGFloat(elapsed / duration)
    if percentComplete >= 1.0 {
        percentComplete = 1.0
        stopDisplayLink()
    }
    TopConstraintforMoving1.constant = 390 - 350 * percentComplete
}

let button = UIButton()
var displayLink: CADisplayLink?
var startTime: CFAbsoluteTime?
let duration = 2.0
var topConstraint: NSLayoutConstraint!
@IBAction func start(sender: UIButton) {
    displayLink?.invalidate()
    startTime = CFAbsoluteTimeGetCurrent()
    displayLink = CADisplayLink(target: self, selector: "handleDisplayLink:")
    displayLink?.addToRunLoop(NSRunLoop.mainRunLoop(), forMode: NSRunLoopCommonModes)
}
func handleDisplayLink(displayLink: CADisplayLink) {
    button.hidden = false
    let elapsed = CFAbsoluteTimeGetCurrent() - startTime!
    var percentComplete = CGFloat(elapsed / duration)
    if percentComplete >= 1.0 {
        percentComplete = 1.0
        displayLink.invalidate()
        button.hidden = true
    }
    topConstraint.constant = 393 - 350 * percentComplete
    NSLayoutConstraint.activateConstraints([
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 122),
        topConstraint,
        button.widthAnchor.constraintEqualToConstant(75),
        button.heightAnchor.constraintEqualToConstant(75)
        ])
}
func buttonPressed(sender: UIButton!) {
    button.hidden = true
    displayLink?.invalidate()
}
override func viewDidLoad() {
    super.viewDidLoad()
    button.hidden = true
    button.setImage(UIImage(named: "BlueBall.png")!, forState: UIControlState.Normal)
    button.addTarget(self, action: "buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
    self.view.addSubview(button)
    button.translatesAutoresizingMaskIntoConstraints = false
    topConstraint = button.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 393)  
    NSLayoutConstraint.activateConstraints([
        button.leadingAnchor.constraintEqualToAnchor(view.leadingAnchor, constant: 122),
        topConstraint,
        button.widthAnchor.constraintEqualToConstant(75),
        button.heightAnchor.constraintEqualToConstant(75)
        ])   
}

---

如何将实例保存到约束？您的意思是如何将约束保存到实例变量？请参阅对我答案的编辑。因此，要创建topConstraintforMoving1，我必须执行以下操作：var topConstraintforMoving1=NSLaysoutConstraint（）？否。您需要var

var topConstraintforMoving1:NSLaysoutConstraint

。您不应该在变量声明中创建NSLaysoutConstraint的实例，因为它永远不会被使用。谢谢。现在在顶部（class（name）：UIViewController{//code}），它说：class（name）没有初始值设定项btw，不建议使用CADisplayLink并在每个帧上手动更改约束的常量。最好使用UIVIEW动画，比如动画动画：动画：在那里你改变了约束，并调用动画块内的LayuthIdvices。Ya，但是我不能点击动画中间的按钮“Ya，但是我不能点击动画中间的按钮”“是的，你可以。”也许你问一下会更好@matt我正在阅读您关于UIButton动画的评论，我同意您关于使用UIVIew动画块的说法，但我目前在UIWebView中面临类似的问题。当webView设置动画时，它变得不可触摸，并且无法将触摸事件转发到webView内容。您建议如何使用CADisplayLink更改约束？“您建议如何使用CADisplayLink更改约束”相同答案。我不会的。