Question

我需要一些帮助，拖动UIView以显示主视图下方的菜单视图。

我有两个UIView个。 menuView - 包括菜单按钮和标签和mainView - 位于menuView之上。

我想从左边缘拖动主视图以显示菜单项并将主视图捕捉到特定位置。我可以将拖动向右移动，但是当向左拖动时我无法将其设置回原始位置。

这是我一直在玩的代码，但没有成功。当我向右拖动时，我也想让mainView变小。任何帮助将不胜感激。

注意：PanGesture附加到mainView。

@IBAction func dragMenu(_ sender: UIPanGestureRecognizer) {
    let mview = sender.view!
    let originalCenter = CGPoint(x: self.mainView.bounds.width/2, y: self.mainView.bounds.height/2)
    switch sender.state {

    case .changed:
        if let mview = sender.view {
            mview.center.x = mview.center.x + sender.translation(in: view).x
            sender.setTranslation(CGPoint.zero, in: view)
        }

    case .ended:


            let DraggedHalfWayRight = mview.center.x > view.center.x
            if DraggedHalfWayRight {
                //dragginToRight

                showMenu = !showMenu
                self.mainViewRight.constant = 200
                                    self.mainTop.constant = 50
                                    self.mainBottom.constant = 50
                                    self.mainLeft.constant = 200

            } else //dragging left and set it back to original position.
            {
                mview.center = originalCenter
                 showMenu = !showMenu
        }



    default:
        break
    }
}

Answer 1

我建议一些事情：

当您完成拖动菜单后，请确保将其alpha设置为零（如果您是在纵向并转到横向，则不要突然看到菜单坐在那里。
我个人只是调整拖动视图的transform，并避免将手势的平移重置为零。这是个人偏好的问题。
我将视图控制器作为手势的委托并实现gestureRecognizerShouldBegin（因为如果菜单被隐藏，您不想识别滑动以尝试再次隐藏它;如果它不是隐藏的，你不想识别滑动以显示它。）
在确定是否完成手势时，我还会考虑手势的速度（例如，稍微轻弹就会消除/显示动画视图）。

因此：

class ViewController: UIViewController {

    @IBOutlet weak var menuView: UIView!

    var isMenuVisible = true

    @IBAction func dragMenu(_ gesture: UIPanGestureRecognizer) {
        let translationX = gesture.translation(in: gesture.view!).x

        switch gesture.state {
        case .began:
            // if the menu is not visible, make sure it's off screen and then make it visible

            if !isMenuVisible {
                menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
                menuView.alpha = 1
            }
            fallthrough

        case .changed:
            if isMenuVisible {
                menuView.transform = CGAffineTransform(translationX: translationX, y: 0)
            } else {
                menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width + translationX, y: 0)
            }

        case .ended:
            let shouldComplete: Bool
            if isMenuVisible {
                shouldComplete = translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x > 0
            } else {
                shouldComplete = -translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x < 0
            }

            UIView.animate(withDuration: 0.25, animations: {
                if self.isMenuVisible && shouldComplete || !self.isMenuVisible && !shouldComplete {
                    self.menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
                } else {
                    self.menuView.transform = .identity
                }

                if shouldComplete{
                    self.isMenuVisible = !self.isMenuVisible
                }
            }, completion: { _ in
                self.menuView.alpha = self.isMenuVisible ? 1 : 0
            })

        default:
            break
        }
    }

}

extension ViewController: UIGestureRecognizerDelegate {

    func gestureRecognizerShouldBegin(_ gesture: UIGestureRecognizer) -> Bool {
        guard let gesture = gesture as? UIPanGestureRecognizer else { return true }

        let translationX = gesture.translation(in: gesture.view!).x

        return isMenuVisible && translationX > 0 || !isMenuVisible && translationX < 0
    }

}

就个人而言，我更喜欢使用单独的屏幕边缘手势识别器将它们拉回到屏幕上（你真的不希望它在任何地方识别手势，而只是在右边缘）。这种方法的另一个优点是通过在不同的函数中保持“显示”和“隐藏”，代码更具可读性（恕我直言）：

class ViewController: UIViewController {

    @IBOutlet weak var menuView: UIView!

    var isMenuVisible = true

    @IBAction func handleScreenEdgeGesture(_ gesture: UIScreenEdgePanGestureRecognizer) {
        let translationX = gesture.translation(in: gesture.view!).x

        switch gesture.state {
        case .began:
            menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
            menuView.alpha = 1
            fallthrough

        case .changed:
            menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width + translationX, y: 0)

        case .ended:
            let shouldComplete = -translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x < 0

            UIView.animate(withDuration: 0.25, delay:0, options: .curveEaseOut, animations: {
                if shouldComplete {
                    self.menuView.transform = .identity
                    self.isMenuVisible = !self.isMenuVisible
                } else {
                    self.menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
                }
            }, completion: { _ in
                self.menuView.alpha = self.isMenuVisible ? 1 : 0
            })

        default:
            break
        }
    }

    @IBAction func dragMenu(_ gesture: UIPanGestureRecognizer) {
        let translationX = gesture.translation(in: gesture.view!).x

        switch gesture.state {
        case .began, .changed:
            menuView.transform = CGAffineTransform(translationX: translationX, y: 0)

        case .ended:
            let shouldComplete = translationX > gesture.view!.bounds.width / 2 || gesture.velocity(in: gesture.view!).x > 0

            UIView.animate(withDuration: 0.25, delay:0, options: .curveEaseOut, animations: {
                if shouldComplete {
                    self.menuView.transform = CGAffineTransform(translationX: gesture.view!.bounds.width, y: 0)
                    self.isMenuVisible = !self.isMenuVisible
                } else {
                    self.menuView.transform = .identity
                }
            }, completion: { _ in
                self.menuView.alpha = self.isMenuVisible ? 1 : 0
            })

        default:
            break
        }
    }

}

extension ViewController: UIGestureRecognizerDelegate {

    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if gestureRecognizer is UIScreenEdgePanGestureRecognizer {
            return !isMenuVisible
        } else if let gesture = gestureRecognizer as? UIPanGestureRecognizer {
            let translationX = gesture.translation(in: gesture.view!).x
            return isMenuVisible && translationX > 0
        }

        return true
    }

}

拖动UIView

1 个答案: