swift中UIScrollView的使用（图片缩放）

github学习地址：https://github.com/potato512/SYSwiftLearning

关键源码

注意事项：

（1）缩放时将图片视图UIImageView的父视图设置为UIScrollView（A），然后再将UIScrollView的父视图设置为UIScrollView（B）；同时设置A的delegate方法，以及设置B的contentSize；

（2）缩放时将图片一直居中显示，即在代理方法"scrollViewDidZoom"中设置；

@H_502_53@// MARK: - 视图 func setUI() { self.mainScrollView = UIScrollView(frame: CGRectMake(0.0,0.0,CGRectGetWidth(self.view.bounds),280.0)) // 添加到父视图 self.view.addSubview(self.mainScrollView) // 添加子视图label var originX:CGFloat = 0.0 for number in 1...3 { let scrollview = UIScrollView(frame: CGRectMake(originX,CGRectGetWidth(self.mainScrollView.bounds),CGRectGetHeight(self.mainScrollView.bounds))) self.mainScrollView.addSubview(scrollview) if 1 == number { scrollview.backgroundColor = UIColor.brownColor() } else if 2 == number { scrollview.backgroundColor = UIColor.blueColor() } else { scrollview.backgroundColor = UIColor.orangeColor() } let imageview = UIImageView(frame: scrollview.bounds) scrollview.addSubview(imageview); imageview.contentMode = .ScaleAspectFit imageview.backgroundColor = UIColor.purpleColor() var image = UIImage(named: "01") if 2 == number { image = UIImage(named: "02") } else if 3 == number { image = UIImage(named: "03") } imageview.image = image originX = (CGRectGetMinX(scrollview.frame) + CGRectGetWidth(scrollview.frame)) // 两个手指拿捏缩放 scrollview.minimumZoomScale = 0.3 scrollview.maximumZoomScale = 2.0 scrollview.delegate = self // 双击缩放 let doubleTap = UITapGestureRecognizer(target: self,action: Selector("doubleClick:")) doubleTap.numberOfTapsrequired = 2 imageview.userInteractionEnabled = true imageview.addGestureRecognizer(doubleTap) } // 背景颜色 self.mainScrollView.backgroundColor = UIColor(red: CGFloat(CGFloat(random()) / CGFloat(RAND_MAX)),green: CGFloat(CGFloat(random()) / CGFloat(RAND_MAX)),blue: CGFloat(CGFloat(random()) / CGFloat(RAND_MAX)),alpha: 1.0) // 其他属性 self.mainScrollView.scrollEnabled = true // 可以上下滚动 self.mainScrollView.scrollsToTop = true // 点击状态栏时，可以滚动回顶端 self.mainScrollView.bounces = true // 反弹效果，即在最顶端或最底端时，仍然可以滚动，且释放后有动画返回效果 self.mainScrollView.pagingEnabled = true // 分页显示效果 self.mainScrollView.showsHorizontalScrollIndicator = true // 显示水平滚动条 self.mainScrollView.showsVerticalScrollIndicator = true // 显示垂直滚动条 self.mainScrollView.indicatorStyle = UIScrollViewIndicatorStyle.White // 滑动条的样式 // 设置内容大小 self.mainScrollView.contentSize = CGSizeMake(originX,CGRectGetHeight(self.mainScrollView.bounds)) }

// MARK: - UIScrollViewDelegate
func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView?
{
        print("1 scrollViewDidZoom")
        
        // 设置被缩放的对应视图
        for imageview in scrollView.subviews
        {
            if imageview is UIImageView
            {
                return imageview
            }
        }
        
        return nil
}
    
func scrollViewWillBeginZooming(scrollView: UIScrollView,withView view: UIView?)
{
        print("2 scrollViewWillBeginZooming")
        
        print("view = \(view)")
}
    
func scrollViewDidZoom(scrollView: UIScrollView)
{
        print("3 scrollViewDidZoom")
        
        // 居中显示
        let imageview = scrollView.subviews.first as! UIImageView
        self.centerShow(scrollView,imageview: imageview)
}
    
func scrollViewDidEndZooming(scrollView: UIScrollView,withView view: UIView?,atScale scale: CGFloat)
{
        print("4 scrollViewDidEndZooming")
        
        print("scale = \(scale)，view = \(view)")
        
        // 缩放效果
        // 放大或缩小
        if scrollView.minimumZoomScale >= scale
        {
            scrollView.setZoomScale(0.3,animated: true)
        }
        if scrollView.maximumZoomScale <= scale
        {
            scrollView.setZoomScale(2.0,animated: true)
        }
}

// MARK: - 双击缩放
var isScaleBig:Bool = false
func doubleClick(gestureRecognizer:UITapGestureRecognizer)
{
        let imageview = gestureRecognizer.view as! UIImageView
        let scrollview = imageview.superview as! UIScrollView
        
        // 放大缩小
        let scale = scrollview.zoomScale
        if isScaleBig
        {
            scrollview.setZoomScale((scale / 0.3),animated: true)
            isScaleBig = false
        }
        else
        {
            scrollview.setZoomScale((scale * 0.3),animated: true)
            isScaleBig = true
        }
}

func centerShow(scrollview:UIScrollView,imageview:UIImageView)
{
        // 居中显示
        let offsetX = (scrollview.bounds.size.width > scrollview.contentSize.width) ? (scrollview.bounds.size.width - scrollview.contentSize.width) * 0.5 : 0.0;
        let offsetY = (scrollview.bounds.size.height > scrollview.contentSize.height) ?
        (scrollview.bounds.size.height - scrollview.contentSize.height) * 0.5 : 0.0;
        imageview.center = CGPointMake(scrollview.contentSize.width * 0.5 + offsetX,scrollview.contentSize.height * 0.5 + offsetY);
}

swift中UIScrollView的使用（图片缩放）

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