swift 点击图片预览，有放大缩小动画

//Cell的点击事件
let rect = targetCell.convert(targetCell.chatImageView.frame, to: self.listTableView)
let rect2 = self.listTableView.convert(rect, to: self.view)
                
//获取状态栏的rect
let statusRect = UIApplication.shared.statusBarFrame
//获取导航栏的rect
let navRect = self.navigationController?.navigationBar.frame
let navBarHeight = statusRect.height + (navRect?.height)!
                
let tapFrame = CGRect.init(x: rect2.origin.x, y: rect2.origin.y + navBarHeight, width: rect2.width, height: rect2.height)
let image = targetCell.chatImageView.image
showZoomImageView(image, tapFrame:tapFrame)

//图片缩放动画
func showZoomImageView(image:UIImage, tapFrame:CGRect) {
        let bgView = UIScrollView.init(frame: UIScreen.main.bounds)
        bgView.backgroundColor = UIColor.clear
        let tapBg = UITapGestureRecognizer.init(target: self, action: #selector(tapBgView(tapBgRecognizer:)))
        bgView.addGestureRecognizer(tapBg)
        let tmpImageView = UIImageView.init()

        tmpImageView.setImage(image, "default_image")

        tmpImageView.frame = bgView.frame
        tmpImageView.contentMode = .scaleAspectFit
        bgView.addSubview(tmpImageView)
        UIApplication.shared.keyWindow?.addSubview(bgView)
        self.lastImageView = tmpImageView
        self.originalFrame = tapFrame
        self.scrollView = bgView
        self.scrollView?.maximumZoomScale = 3.0
        self.scrollView?.minimumZoomScale = 1.0
        self.scrollView?.delegate = self

        self.lastImageView?.frame = self.originalFrame
        UIView.animate(
            withDuration: 0.5,
            delay: 0.0,
            options: UIViewAnimationOptions.beginFromCurrentState,
            animations: {
                self.lastImageView?.frame = (self.scrollView?.bounds)!
                self.scrollView?.backgroundColor = UIColor.black
                self.scrollView?.zoomScale = 1.0
        }, completion: nil
        )
    }
    
    @objc func tapBgView(tapBgRecognizer:UITapGestureRecognizer){
        self.scrollView?.contentOffset = CGPoint.zero
        UIView.animate(withDuration: 0.3, animations: {
            self.lastImageView?.frame = self.originalFrame
            tapBgRecognizer.view?.backgroundColor = UIColor.clear
        }) { (finished:Bool) in
            tapBgRecognizer.view?.removeFromSuperview()
            self.scrollView = nil
            self.lastImageView = nil
        }
    }

    //可缩放的view
    func viewForZooming(in scrollView: UIScrollView) -> UIView? {
        return self.lastImageView
    }
    
    //缩放响应，设置imageView的中心位置
    func scrollViewDidZoom(_ scrollView: UIScrollView) {
        var centerX = scrollView.center.x
        var centerY = scrollView.center.y
        centerX = scrollView.contentSize.width > scrollView.frame.size.width ?
            scrollView.contentSize.width/2:centerX
        centerY = scrollView.contentSize.height > scrollView.frame.size.height ?
            scrollView.contentSize.height/2:centerY
        self.lastImageView?.center = CGPoint(x: centerX, y: centerY)
    }