带有平移、旋转和捏合手势的 UIKit Dynamics

Posted 2023-02-23

【中文标题】带有平移、旋转和捏合手势的 UIKit Dynamics

【英文标题】：UIKit Dynamics with pan, rotate and pinch gesture

【发布时间】：2017-07-06 12:32:06

【问题描述】：

我已将 UIDynamics 添加到 imageview 并为此使用了平移手势。使用平移手势可以正常工作，但是当我应用捏合手势时它不起作用。它显示大图像视图，但是当我开始拖动时，它会更改为原始大小。

这是我的代码：

func handleAttachmentGesture(_ sender: UIPanGestureRecognizer) 
    let location = sender.location(in: emojiSuperView!)
    let boxLocation = sender.location(in: self)
    switch sender.state 
    case .began:
        print("Your touch start position is \(location)")
        print("Start location in image is \(boxLocation)")

        animator.removeAllBehaviors()

        let centerOffset = UIOffset(horizontal: boxLocation.x - self.bounds.midX, vertical: boxLocation.y - self.bounds.midY)
        attachmentBehavior = UIAttachmentBehavior(item: self, offsetFromCenter: centerOffset, attachedToAnchor: location)
        animator.addBehavior(attachmentBehavior)
    case .ended:
        print("Your touch end position is \(location)")
        print("End location in image is \(boxLocation)")

        animator.removeAllBehaviors()

        // 1
        let velocity = sender.velocity(in: emojiSuperView!)
        let magnitude = sqrt((velocity.x * velocity.x) + (velocity.y * velocity.y))

        if magnitude > ThrowingThreshold 
            // 2
            let pushBehavior = UIPushBehavior(items: [self], mode: .instantaneous)
            pushBehavior.pushDirection = CGVector(dx: velocity.x / 10, dy: velocity.y / 10)
            pushBehavior.magnitude = magnitude / ThrowingVelocityPadding

            self.pushBehavior = pushBehavior
            animator.addBehavior(pushBehavior)

            // 3
            let angle = Int(arc4random_uniform(20)) - 10

            itemBehavior = UIDynamicItemBehavior(items: [self])
            itemBehavior.friction = 0.2
            itemBehavior.allowsRotation = true
            itemBehavior.addAngularVelocity(CGFloat(angle), for: self)
            animator.addBehavior(itemBehavior)
        
    default:
        attachmentBehavior.anchorPoint = sender.location(in: emojiSuperView!)
        break
    



func recognizePinchGesture(sender: UIPinchGestureRecognizer)

    weak var dynamicItem: UIDynamicItem?
    // whatever your item is, probably a UIView
    dynamicItem = self
    let behavior = UIGravityBehavior(items: [dynamicItem!])
    let animator = UIDynamicAnimator(referenceView: emojiSuperView!)
    // or however you're getting your animator
    animator.addBehavior(behavior)
    sender.view!.transform = sender.view!.transform.scaledBy(x: sender.scale, y: sender.scale)
    animator.updateItem(usingCurrentState: self)
    self.animator.updateItem(usingCurrentState: self)
    sender.scale = 1

【问题讨论】：

好问题 +1 ???? ，我也面临同样的问题，

您的视图控制器看起来如何？你有公开的吗？

【参考方案1】：

当用户执行任何变换事件时，将当前变换保存到全局变量。

之后，当平移开始时，使用 UIAttachmentBehavior 的 action 属性在开始状态下分配新的变换。

        attachmentBehavior.action = 
            self.attachmentBehavior.items[0].transform = self.aTransform