swift中UIScrollView的使用（常规使用，以及contentInset属性设

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

效果图：

关键源码

func setUI()
{
        let mainScrollView = UIScrollView(frame: self.view.bounds)
        
        // 添加到父视图
        self.view.addSubview(mainScrollView)
        
        // 添加子视图label
        var originY:CGFloat = 10.0
        for number in 1...10
        {
            let label = UILabel(frame: CGRectMake(10.0,originY,(CGRectGetWidth(mainScrollView.bounds) - 10.0 * 2),200.0))
            mainScrollView.addSubview(label)
            label.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)
            label.textAlignment = .Center
            label.text = String(format: "scrollView add 第 %ld 个 label",arguments: [number]);
            
            originY = (CGRectGetMinY(label.frame) + CGRectGetHeight(label.frame) + 10.0)
        }
        
        // 背景颜色
        mainScrollView.backgroundColor = UIColor(red: CGFloat(CGFloat(random()) / CGFloat(RAND_MAX)),alpha: 1.0)
        // 自适应父视图
        mainScrollView.autoresizingMask = UIViewAutoresizing.FlexibleHeight
        // 其他属性
        mainScrollView.scrollEnabled = true // 可以上下滚动
        mainScrollView.scrollsToTop = true // 点击状态栏时，可以滚动回顶端
        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
        mainScrollView.pagingEnabled = false // 分页显示效果
        mainScrollView.showsHorizontalScrollIndicator = true // 显示水平滚动条
        mainScrollView.showsVerticalScrollIndicator = true // 显示垂直滚动条
        mainScrollView.indicatorStyle = UIScrollViewIndicatorStyle.White // 滑动条的样式
        // 设置内容大小
        mainScrollView.contentSize = CGSizeMake(CGRectGetWidth(self.view.bounds),originY)
        // 设置代理
        mainScrollView.delegate = self
        
        
        
        // 头尾视图
        self.headerLabel = UILabel(frame: CGRectMake(0.0,0.0,CGRectGetWidth(self.view.frame),0.0))
        self.view.addSubview(self.headerLabel)
        self.headerLabel.backgroundColor = UIColor.yellowColor()
        self.headerLabel.textColor = UIColor.redColor()
        self.headerLabel.textAlignment = .Center
        self.headerLabel.text = "headerLabel"
        self.headerLabel.hidden = false
        
        self.footerLabel = UILabel(frame: CGRectMake(0.0,(CGRectGetHeight(self.view.frame) - 40.0),0.0))
        self.view.addSubview(self.footerLabel)
        self.footerLabel.autoresizingMask = .FlexibleTopMargin
        self.footerLabel.backgroundColor = UIColor.yellowColor()
        self.footerLabel.textColor = UIColor.redColor()
        self.footerLabel.textAlignment = .Center
        self.footerLabel.text = "footerLabel"
        self.footerLabel.hidden = false
}

// MARK: - UIScrollViewDelegate
    
func scrollViewWillBeginDragging(scrollView: UIScrollView)
{
        print("1 scrollViewWillBeginDragging")
        
        scrollView.contentInset = UIEdgeInsetsZero
}
    
func scrollViewDidScroll(scrollView: UIScrollView)
{
        print("2 scrollViewDidScroll")
        
        // 上下拉时滚动时的位移量（向上滚动时，位移是正数；向下拉动时，位移是负数）
        let offsetY = scrollView.contentOffset.y
        print("offsetY = (offsetY)")
        
        // 最大位移量（注意scrollview的contentsize的高与当前视图控制器的屏幕高度的关系）
        let offsetYMax = scrollView.contentSize.height
        print("offsetYMax = (offsetYMax)")
        let offsetYTmp = offsetYMax - CGRectGetHeight(self.view.bounds)
        print("offsetYTmp = (offsetYTmp)")
        
        if 0 >= offsetY
        {
            // 向下拉
            
            // 重置headerLabel的frame
            var rectHeader = self.headerLabel.frame
            rectHeader.size.height = offsetY * -1.0
            self.headerLabel.frame = rectHeader
            
            //
            if -100.0 >= offsetY
            {
                scrollView.contentInset = UIEdgeInsetsMake(80.0,0.0)
            }
        }
        else
        {
            // 向上拉
            let offsetYUp = offsetY - offsetYTmp
            
            // 重置footerLabel的frame
            var rectFooter = self.footerLabel.frame
            rectFooter.origin.y = CGRectGetHeight(self.view.bounds) - offsetYUp
            rectFooter.size.height = offsetYUp
            self.footerLabel.frame = rectFooter
            
            
            //
            if 100.0 <= offsetYUp
            {
                scrollView.contentInset = UIEdgeInsetsMake(0.0,80.0,0.0)
            }
        }
}
    
func scrollViewWillEndDragging(scrollView: UIScrollView,withVelocity velocity: CGPoint,targetContentOffset: UnsafeMutablePointer<CGPoint>)
{
        print("3 scrollViewWillEndDragging")
}
    
func scrollViewDidEndDragging(scrollView: UIScrollView,willDecelerate decelerate: Bool)
{
        print("4 scrollViewDidEndDragging")
}
    
func scrollViewWillBeginDecelerating(scrollView: UIScrollView)
{
        print("5 scrollViewWillBeginDecelerating")
}
    
func scrollViewDidEndDecelerating(scrollView: UIScrollView)
{
        print("6 scrollViewDidEndDecelerating")
        

}

（编辑：李大同）

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