改变UIView的高度以响应手指拖动

Question

我知道标题有点令人困惑所以我会尽力解释它。 我有一个固定宽度为100的UIView，以及从0开始的可变高度。我想要做的是将手指从UIView的底部拖到屏幕顶部，以及UIView改变它的高度/延伸到我的手指的位置。 如果那仍然复杂只是想象它是从一些东西拉出来的纸条。

如果你能提供帮助，那真的很棒。 我认为它不应该太难，但我只是一个初学者，如果我没有解释好的话，我可以理解！

Answer 1

这应该是直接的UIPanGestureRecognizer和一点点数学。 要将视图更改为正确的框架（我使用名称_viewToChange ，请稍后将其替换为您的视图），只需添加：

UIPanGestureRecognizer * pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
pan.maximumNumberOfTouches = pan.minimumNumberOfTouches = 1;
[self addGestureRecognizer:pan];

到超级视图的init方法，并定义方法：

- (void)pan:(UIPanGestureRecognizer *)aPan; {
  CGPoint currentPoint = [aPan locationInView:self];

  [UIView animateWithDuration:0.01f
                   animations:^{
                     CGRect oldFrame = _viewToChange.frame;
                     _viewToChange.frame = CGRectMake(oldFrame.origin.x, currentPoint.y, oldFrame.size.width, ([UIScreen mainScreen].bounds.size.height - currentPoint.y));
                   }];
}

这应该在用户手指移动时为视图设置动画。 希望有帮助！

Answer 2

使用UIPanGestureRecognizer的Swift版本

使用PanGesture从Storyboard添加到UIView并将set委托给self。 UIView附在屏幕的底部。

class ViewController: UIViewController {
var translation: CGPoint!
var startPosition: CGPoint! //Start position for the gesture transition
var originalHeight: CGFloat = 0 // Initial Height for the UIView
var difference: CGFloat!

override func viewDidLoad() {
    super.viewDidLoad()
    originalHeight = dragView.frame.height
}

@IBOutlet weak var dragView: UIView! // UIView with UIPanGestureRecognizer

@IBOutlet var gestureRecognizer: UIPanGestureRecognizer!

@IBAction func viewDidDragged(_ sender: UIPanGestureRecognizer) {

    if sender.state == .began {
        startPosition = gestureRecognizer.location(in: dragView) // the postion at which PanGestue Started
    }

    if sender.state == .began || sender.state == .changed {
        translation = sender.translation(in: self.view)
        sender.setTranslation(CGPoint(x: 0.0, y: 0.0), in: self.view)
        let endPosition = sender.location(in: dragView) // the posiion at which PanGesture Ended
        difference = endPosition.y - startPosition.y
        var newFrame = dragView.frame
        newFrame.origin.x = dragView.frame.origin.x
        newFrame.origin.y = dragView.frame.origin.y + difference //Gesture Moving Upward will produce a negative value for difference
        newFrame.size.width = dragView.frame.size.width
        newFrame.size.height = dragView.frame.size.height - difference //Gesture Moving Upward will produce a negative value for difference
        dragView.frame = newFrame
    }

    if sender.state == .ended || sender.state == .cancelled {
        //Do Something
    }
  }
}

Answer 3

这是我在使用自动布局和要调整大小的视图上的高度约束时使用自动布局的快速解决方案，同时根据安全区域设置顶部和底部限制

private var startPosition: CGPoint!
private var originalHeight: CGFloat = 0

override func viewDidLoad() {
    super.viewDidLoad()

    let panGesture = UIPanGestureRecognizer(target: self, action: #selector(viewDidDrag(_:)))
    resizableView.addGestureRecognizer(panGesture)
}

@objc private func viewDidDrag(_ sender: UIPanGestureRecognizer) {
    if sender.state == .began  {
        startPosition = sender.location(in: self.view)
        originalHeight = detailsContainerViewHeight.constant
    }

    if sender.state == .changed {
        let endPosition = sender.location(in: self.view)
        let difference = endPosition.y - startPosition.y
        var newHeight = originalHeight - difference

        if view.bounds.height - newHeight < topSafeArea + backButtonSafeArea {
            newHeight = view.bounds.height - topSafeArea - backButtonSafeArea
        } else if newHeight < routeDetailsHeaderView.bounds.height + bottomSafeArea {
            newHeight = routeDetailsHeaderView.bounds.height
        }

        resizableView.constant = newHeight
    }

    if sender.state == .ended || sender.state == .cancelled {
        //Do Something if interested when dragging ended.
    }
}