动画视图跳转到最终位置而不是缓慢移动答案

【问题标题】：Animating View jumps to final position instead of slow movement动画视图跳转到最终位置而不是缓慢移动
【发布时间】：2017-04-21 12:05:57
【问题描述】：

我正在制作包含 ImageView 和 Label 的视图动画。请参见图 1。当在 tableView 上滚动完成时，我正在尝试为 upperView 设置动画。最终的结果应该如图 2 所示。其中 imageView 的高度和宽度减小了，并且位于左角，并且在 imageView 前面具有最小高度和标签。动画工作正常，imageView 从原始位置顺利到达最终位置，Label 也是如此。但是根据动画，upperView 不起作用。

我尝试了使用 upperViews 高度约束和框架。

如果我用它的高度约束来改变它，它会很快到达它的最终位置。
如果我使用 upperView.frame.size.height 给出高度，那么视图会上升，但表格视图仍保留在原位。

这是我尝试过的

func scrollViewDidScroll(scrollView: UIScrollView) {
  if scrollView.contentOffset.y > 0
        {
         UIView.animateWithDuration(1.5, delay: 0.0, options: .CurveEaseOut, animations:
                    {
                        self.imageView.frame = CGRect(x: 5.0, y: 0.0, width: 30, height: 40)

                    }, completion: { finished in
                        UIView.animateWithDuration(1.5, delay: 1.0, options: UIViewAnimationOptions.AllowUserInteraction,animations: {

                            self.selectedProgramNameLabel.center = CGPoint(x: self.selectedProgramNameLabel.center.x, y: self.imageView.center.y)

                            }, completion: { finished in
                                UIView.animateWithDuration(1.5, delay: 2.0, options: UIViewAnimationOptions.AllowUserInteraction, animations: {

                              self.upperViewHeightConstraint.constant = 50

                                    }, completion: { finished in

                                })
                        })
                })
        }
        else if scrollView.contentOffset.y == 0
        {
          UIView.animateWithDuration(1.5, delay: 0.0, options: .CurveEaseOut, animations:
                {
                    self.selectedProgramNameLabel.center = CGPoint(x: self.selectedProgramNameLabel.center.x, y: self.imageView.center.y + self.imageView.frame.height - 45)


                }, completion: { finished in
                    UIView.animateWithDuration(1.5, delay: 0.0, options: UIViewAnimationOptions.AllowUserInteraction,animations: {

                        self.imageView.frame = CGRect(x: self.upperView.frame.origin.x, y: self.upperView.frame.origin.y, width: 100.0, height: 134)


                        }, completion: { finished in
                            UIView.animateWithDuration(1.5, delay: 1.0, options: UIViewAnimationOptions.AllowUserInteraction, animations: {


                                }, completion: { finished in


                            })
                    })
            })

       }

TIA。

图 1。图 2。

【问题讨论】：

标签： ios iphone swift swift2.3

【解决方案1】：

在为任何布局约束设置动画时，如果您想要想要的动画效果，必须在动画块中使用layoutIfNeeded。所以只需在动画块中添加这个。

self.view.layoutIfNeeded()
self.upperViewHeightConstraint.constant = 50

还可以使用任何标志来检查视图是否已动画化，否则您的动画块将执行多次。

【讨论】：

我之前尝试过 self.view.layoutIfNeeded() ，但它的作用仍然相同。跳转到最终位置。
你的动画块被执行了多次，让它们动画一次。
是的，我让它执行一次，但它仍然没有动画。它跳了:(
你是说上视图没有动画对吧？
是的，伙计。它直接跳转到高度 50

【解决方案2】：

尝试使用：UIViewAnimationOptions.beginFromCurrentState、CABasicAnimation。 How to animate the frame of an layer with CABasicAnimation?

这不是你要找的东西，但我希望它能帮助你。

var cntTopViewT: NSLayoutConstraint!
var cntTopViewH: NSLayoutConstraint!

override func viewDidLoad() {
    super.viewDidLoad()

    navigationController?.navigationBar.setBackgroundImage(UIImage(), for: UIBarMetrics.default)
    navigationController?.navigationBar.shadowImage = UIImage()
    navigationController?.navigationBar.isTranslucent = true

    let scrollView = UIScrollView()
    scrollView.delegate = self
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(scrollView)

    let topView = UIView()
    topView.translatesAutoresizingMaskIntoConstraints = false
    scrollView.addSubview(topView)

    let topViewBackgroundImageView = UIImageView()
    topViewBackgroundImageView.translatesAutoresizingMaskIntoConstraints = false
    topView.addSubview(topViewBackgroundImageView)

    let bottomView = UIView()
    bottomView.translatesAutoresizingMaskIntoConstraints = false
    scrollView.insertSubview(bottomView, at: 0)

    let v = UIView()
    v.translatesAutoresizingMaskIntoConstraints = false
    bottomView.addSubview(v)


    let views: [String: Any] = ["view": view,
                                "scrollView": scrollView,
                                "topView": topView,
                                "topViewBackgroundImageView": topViewBackgroundImageView,
                                "bottomView": bottomView,
                                "v": v]
    var cnts: [NSLayoutConstraint] = []

    cnts += NSLayoutConstraint.constraints(withVisualFormat: "H:|[scrollView]|", options: [], metrics: nil, views: views)
    cnts += NSLayoutConstraint.constraints(withVisualFormat: "V:|[scrollView]|", options: [], metrics: nil, views: views)

    cnts += NSLayoutConstraint.constraints(withVisualFormat: "H:[topView(scrollView)]", options: [], metrics: nil, views: views)
    cnts += NSLayoutConstraint.constraints(withVisualFormat: "V:[scrollView]-0@1-[topView]", options: [.alignAllCenterX], metrics: nil, views: views)
    cntTopViewT = NSLayoutConstraint(item: topView, attribute: .top, relatedBy: .equal, toItem: scrollView, attribute: .top, multiplier: 1, constant: 0)
    cntTopViewH = NSLayoutConstraint(item: topView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .height, multiplier: 1, constant: 0)
    cnts += [cntTopViewT, cntTopViewH]

    cnts += NSLayoutConstraint.constraints(withVisualFormat: "H:|[topViewBackgroundImageView]|", options: [], metrics: nil, views: views)
    cnts += NSLayoutConstraint.constraints(withVisualFormat: "V:|[topViewBackgroundImageView]|", options: [], metrics: nil, views: views)

    cnts += [NSLayoutConstraint(item: bottomView, attribute: .width, relatedBy: .equal, toItem: scrollView, attribute: .width, multiplier: 0.9, constant: 0)]
    cnts += NSLayoutConstraint.constraints(withVisualFormat: "V:[scrollView]-0@1-[bottomView]|", options: [.alignAllCenterX], metrics: nil, views: views)
    cnts += NSLayoutConstraint.constraints(withVisualFormat: "V:|[bottomView(999)]|", options: [], metrics: nil, views: views)

    cnts += NSLayoutConstraint.constraints(withVisualFormat: "H:|[v(50)]", options: [], metrics: nil, views: views)
    cnts += NSLayoutConstraint.constraints(withVisualFormat: "V:|[v(50)]", options: [], metrics: nil, views: views)

    NSLayoutConstraint.activate(cnts)

    topView.backgroundColor = .red
    bottomView.backgroundColor = .green
    v.backgroundColor = .blue
}

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let minH = (navigationController?.navigationBar.frame.height ?? 0) + UIApplication.shared.statusBarFrame.height
    let maxH = view.frame.height * 0.35

    cntTopViewT.constant = scrollView.contentOffset.y
    cntTopViewH.constant = max(-scrollView.contentOffset.y, minH)
    scrollView.contentInset.top = maxH
    scrollView.scrollIndicatorInsets.top = (cntTopViewH.constant - minH) + (minH * ((cntTopViewH.constant - minH) / (maxH - minH))) + 5

    //let kTransform = min(max(cntTopViewH.constant / maxH + 0.1, 0.5), 1)
    //topViewFioLabel.transform = CGAffineTransform(a: kTransform, b: 0, c: 0, d: kTransform, tx: 0, ty: 0)
}

【讨论】：

谢谢你的回答，但我以前试过这个。这只有在表格视图上有足够的数据可以滚动时才有效，否则我的 imageView 和标签会卡在它们之间，看起来很丑陋。因此必须使用 UIAnimation 以便即使表上的数据较少，它也会移动到目的地。但是，当我制作动画时，upperView 高度约束没有移动，它像子弹一样移动，这是不可接受的。