Swift上View手势控制

前言

对View进行放大缩小、移动、旋转，其实是很常见的需求，最开始在OC上，很早的几年，还是用的touch事件来实现，这种实现方式很繁琐，呈现的效果也不是很好。

后来，苹果也逐步的淘汰了这种方式，出了手势这种模式，极大程度上的缩减了代码量，而且操作简单，上手迅速，OC上手势的使用方式网上比比皆是，这里就不细说，着重介绍Swift View手势控制方法。

实现

添加旋转、缩放、移动手势，如下：

//Rotation
let rotationGestureRecognizer = UIRotationGestureRecognizer(target: self, action: #selector(EditPhotoViewController.rotateView(_:)))
photoImageView?.addGestureRecognizer(rotationGestureRecognizer)

//Scale pinch
let pinchGestureRecognizer = UIPinchGestureRecognizer(target: self, action: #selector(EditPhotoViewController.pinchView(_:)))
photoImageView?.addGestureRecognizer(pinchGestureRecognizer)

//Move
let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(EditPhotoViewController.panView(_:)))
photoImageView?.addGestureRecognizer(panGestureRecognizer)

以下代码使用变量如下：

private var cropFrame = CGRect.zero //图片上限制框的frame

private var latestFrame = CGRect.zero //最大缩放frame

private var rotationAngle: CGFloat = 0.0 //旋转的角度

给变量设置初始值：

private func resetShowImageViewFrame() {
   rotationAngle = 0.0

   photoImageView?.image = originalImage
   photoImageView?.transform = .identity

   // scale to fit the screen
   cropFrame = photoOverLayView?.transparentArea ?? CGRect.zero

   var oriWidth: CGFloat = cropFrame.size.width
   var oriHeight: CGFloat = (originalImage?.size.height ?? 0.0) * (oriWidth / (originalImage?.size.width ?? 0.0))
   if ((originalImage?.size.width)!/(originalImage?.size.height)!) > (CGFloat)(standardPostImgWidth)/(CGFloat)(standardPostImgHeight) {
      oriHeight = cropFrame.size.height
      oriWidth = (originalImage?.size.width ?? 0.0) * (oriHeight / (originalImage?.size.height ?? 0.0))
   }
   let oriX: CGFloat = cropFrame.origin.x + (cropFrame.size.width - oriWidth) / 2
   let oriY: CGFloat = cropFrame.origin.y + (cropFrame.size.height - oriHeight) / 2
   oldFrame = CGRect(x: oriX, y: oriY, width: oriWidth, height: oriHeight)
   latestFrame = oldFrame
   photoImageView?.frame = oldFrame
   largeFrame = CGRect(x: 0, y: 0, width: limitRatio * oldFrame.size.width, height: limitRatio * oldFrame.size.height)
}

旋转实现

@objc func rotateView(_ rotationGestureRecognizer: UIRotationGestureRecognizer?) {
   let view: UIView? = photoImageView
   if rotationGestureRecognizer?.state == .began || rotationGestureRecognizer?.state == .changed {
      view?.transform = (view?.transform.rotated(by: (rotationGestureRecognizer?.rotation)!))!
      rotationAngle = rotationAngle + (rotationGestureRecognizer?.rotation ?? 0.0)
      rotationGestureRecognizer?.rotation = 0
   } else if rotationGestureRecognizer?.state == .ended {
      latestFrame = photoImageView?.frame ?? CGRect.zero
   }
}

缩放实现

@objc func pinchView(_ pinchGestureRecognizer: UIPinchGestureRecognizer?) {
   let view: UIView? = photoImageView
   if pinchGestureRecognizer?.state == .began || pinchGestureRecognizer?.state == .changed {
      if rotationAngle == 0 {
       //narrow
         if (pinchGestureRecognizer?.scale)! <= CGFloat(1.0) && ((photoImageView?.width)! <= cropFrame.size.width || (photoImageView?.height)! <= cropFrame.size.height) {
            return
         }
       }
       //amplification
       if (pinchGestureRecognizer?.scale)! > CGFloat(1.0) && ((photoImageView?.width)! > 5000 || (photoImageView?.height)! > 5000) {
            return
        }
        view?.transform = (view?.transform.scaledBy(x: (pinchGestureRecognizer?.scale)!, y: (pinchGestureRecognizer?.scale)!))!
        pinchGestureRecognizer?.scale = 1
    } else if pinchGestureRecognizer?.state == .ended {
        if rotationAngle == 0 {
            var newFrame: CGRect? = photoImageView?.frame
            //newFrame = handleScaleOverflow(newFrame ?? CGRect.zero)
            newFrame = handleBorderOverflow(newFrame ?? CGRect.zero)
            UIView.animate(withDuration: TimeInterval(BOUNDCE_DURATION), animations: {
            self.photoImageView?.frame = newFrame ?? CGRect.zero
            self.latestFrame = newFrame ?? CGRect.zero
                })
        } else {
            latestFrame = photoImageView?.frame ?? CGRect.zero
        }
    }
}

平移实现

@objc func panView(_ panGestureRecognizer: UIPanGestureRecognizer?)
{
   let view = panGestureRecognizer?.view;
   if (panGestureRecognizer?.state == .began || panGestureRecognizer?.state == .changed) {
       let translation = panGestureRecognizer?.translation(in: view?.superview)
       view?.center = CGPoint(x: (view?.center.x)! + (translation?.x)!, y: (view?.center.y)! + (translation?.y)!)
       panGestureRecognizer?.setTranslation(CGPoint.zero, in: view?.superview)
    } else if panGestureRecognizer?.state == .ended {
        if rotationAngle == 0 {
           //bounce to original frame
           var newFrame: CGRect? = photoImageView?.frame
           newFrame = handleBorderOverflow(newFrame ?? CGRect.zero)
           UIView.animate(withDuration: TimeInterval(BOUNDCE_DURATION), animations: {
               self.photoImageView?.frame = newFrame ?? CGRect.zero
               self.latestFrame = newFrame ?? CGRect.zero
            })
        } else {
           latestFrame = photoImageView?.frame ?? CGRect.zero
        }
    }
}

最终效果