scrollViewDidScroll(_ scrollView: UIScrollView) 到达底部后如何保持 UIButton 浮动？

Question

以下是当前的实现。灰色按钮浮动在滚动视图上。一旦到达黄色视图（滚动视图结束），有没有办法让按钮出现。然后让它漂浮在屏幕的最底部。

我正在使用以下代码：

override func scrollViewDidScroll(scrollView: UIScrollView) {

if (scrollView.contentOffset.y >= (scrollView.contentSize.height - scrollView.frame.size.height)) {
    //reached bottom - how to show button below yellow
    // and keep it floating as shown above
}
}

添加到目前为止我尝试过的其他代码：

    @IBOutlet weak var btnScroll: UIButton!

var startingFrame : CGRect!
var endingFrame : CGRect!

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if (scrollView.contentOffset.y >= (scrollView.contentSize.height - scrollView.frame.size.height)) && self.btnScroll.isHidden {
        self.btnScroll.isHidden = false
        self.btnScroll.frame = startingFrame // outside of screen somewhere in bottom
        UIView.animate(withDuration: 1.0) {
            self.btnScroll.frame = self.endingFrame // where it should be placed
        }
    }
}

func configureSizes() {
    let screenSize = UIScreen.main.bounds
    let screenWidth = screenSize.width
    let screenHeight = screenSize.height

    startingFrame = CGRect(x: 0, y: screenHeight+100, width: screenWidth, height: 100)
    endingFrame = CGRect(x: 0, y: screenHeight-100, width: screenWidth, height: 100)

}

override func viewDidLoad() {
    super.viewDidLoad()

    configureSizes()
}

Answer 1

如果我理解你的话，你想把按钮放在 gif 上显示的位置

试试这个代码：

override func scrollViewDidScroll(scrollView: UIScrollView) {
  if (scrollView.contentOffset.y >= (scrollView.contentSize.height - scrollView.frame.size.height)) && self.button.isHidden {
    self.button.isHidden = false
    self.button.frame = startingFrame // outside of screen somewhere in bottom
    UIView.animate(withDuration: 1.0) {
      self.button.frame = yourFrame // where it should be placed
    }
  }
}

更新

添加此代码以在动画显示之前隐藏您的按钮

override func viewDidLoad() {
    super.viewDidLoad()
    self.button.isHidden = true
    ...
}