swift - 以编程方式为约束设置动画 Swift 3

Question

我有一个 View ，我已经通过约束设置了位置和大小:

    oV.centerXAnchor.constraint(equalTo: self.mapViewController.view.centerXAnchor).isActive = true
    oV.centerYAnchor.constraint(equalTo: self.mapViewController.view.centerYAnchor).isActive = true
    oV.widthAnchor.constraint(equalTo: self.mapViewController.view.widthAnchor, constant: -overlaySpacing).isActive = true
    oV.heightAnchor.constraint(equalTo: self.mapViewController.view.heightAnchor, constant: -overlaySpacing).isActive = true

但是，我希望 oV( View )开始时比这个小，并在一秒钟内动画到最终大小。

oV.centerXAnchor.constraint(equalTo: self.mapViewController.view.centerXAnchor).isActive = true
oV.centerYAnchor.constraint(equalTo: self.mapViewController.view.centerYAnchor).isActive = true
oV.widthAnchor.constraint(equalTo: self.mapViewController.view.widthAnchor, constant: -2 * overlaySpacing).isActive = true
oV.heightAnchor.constraint(equalTo: self.mapViewController.view.heightAnchor, constant: -2 * overlaySpacing).isActive = true

我写的初始约束是常量为 (-2 * overlaySpacing) 的约束。最后的约束条件是宽度/高度常量只是 -overlaySpacing。

我已经以编程方式编写了所有内容，因此 Storyboard 解决方案无济于事。

这是我当前要制作动画的代码，但它只是自动显示为最终约束:

让 oV = NewOverlayView(viewController: mVC, frame: CGRect.zero)

    self.mapViewController.view.addSubview(oV)

    oV.centerXAnchor.constraint(equalTo: self.mapViewController.view.centerXAnchor).isActive = true
    oV.centerYAnchor.constraint(equalTo: self.mapViewController.view.centerYAnchor).isActive = true
    var widthConstraint = oV.widthAnchor.constraint(equalTo: self.mapViewController.view.widthAnchor, constant: -2 * overlaySpacing)
    var heightConstraint = oV.heightAnchor.constraint(equalTo: self.mapViewController.view.heightAnchor, constant: -2 * overlaySpacing)

    widthConstraint.isActive = true
    heightConstraint.isActive = true

    oV.layoutIfNeeded()

    widthConstraint.isActive = false
    heightConstraint.isActive = false

    widthConstraint = oV.widthAnchor.constraint(equalTo: self.mapViewController.view.widthAnchor, constant: -overlaySpacing)
    heightConstraint = oV.heightAnchor.constraint(equalTo: self.mapViewController.view.heightAnchor, constant: -overlaySpacing)

    widthConstraint.isActive = true
    heightConstraint.isActive = true

    UIView.animate(withDuration: 1.0) { oV.layoutIfNeeded() }

谢谢!

Answer 1

属性(property)观察员 proper function对于动画可以是一个解决方案:

1.

使用“didSet”观察器在您的 Controller 中设置一个变量，如下所示:

    var dynamicOverlaySpacing = 0 {
    didSet {
             //Remove previous constraints ?        
             oV.widthAnchor.constraint(equalTo: self.mapViewController.view.widthAnchor, constant: -dynamicOverlaySpacing).isActive = true
             oV.heightAnchor.constraint(equalTo: self.mapViewController.view.heightAnchor, constant: -dynamicOverlaySpacing).isActive = true
        }
    }

每当 dynamicOverlaySpacing 的值发生变化时，都会执行 didSet 闭包中的代码。

2.

创建一个会缓慢改变 dynamicOverlaySpacing 值的动画

像这样的东西应该可以工作:

let delay = 2.0 //the delay you want for the animation
let firstOverlaySpacing = dynamicOverlaySpacing
oV.animate(withDuration: 0, delay: delay, options: .curveEaseIn, animations: {
             dynamicOverlaySpacing = -2*firstOverlaySpacing

            }, completion: nil)

在选项上，我使用 curseEaseIn。您可以看到所有可用选项 here.

我没有尝试代码，但它应该可以工作。