滚动视图

import UIKit

class ViewController: UIViewController {

//获取屏幕的宽

let kScreenWidth = UIScreen.main.bounds.size.width

//获取屏幕的高

let kScreenHeight = UIScreen.main.bounds.size.height

override func viewDidLoad() {

super.viewDidLoad()

//UIScrollView：滚动视图，是所有滚动视图的基类，只要一个视图能够滚动，要么是UIScorllview,要么是UIScollView的子类。UIScollView有两个很重要子类：UITableView,UICollectionView

//什么时候才需要滚动：当我们的内容区域大于可视区域时，为了看到更多内容，才需要去滚动查看

//创建UIScrollView

let scrollView = UIScrollView(frame:CGRect(x: 20, y: 20, width: kScreenWidth - 40, height: kScreenHeight - 40))

scrollView.backgroundColor = #colorLiteral(red: 1, green: 0.4710629376, blue: 0.4618466702, alpha: 1)

//设置scrollView的内容区域大小

scrollView.contentSize = CGSize(width: kScreenWidth*3, height: kScreenHeight*2)

//设置srollView的偏移量(***)

//        scrollView.contentOffset = CGPoint(x: kScreenWidth, y: 0)

//设置滚动条的样式

scrollView.indicatorStyle = .white

//设置是否显示滚动条

//垂直滚动条

scrollView.showsVerticalScrollIndicator = false

//水平滚动条

scrollView.showsHorizontalScrollIndicator = false

//方向锁,滚动的时候只能朝一个方向滚动

scrollView.isDirectionalLockEnabled = true

//设置是否有弹簧效果

//scrollView.bounces = false

//设置是否总是又水平方向弹簧效果

scrollView.alwaysBounceHorizontal = true

//设置是否总是又垂直方向弹簧效果

scrollView.alwaysBounceVertical = true

//设置是否支持整页滚动

scrollView.isPagingEnabled = true

//设置scrollView是否支持滚动

//        scrollView.isScrollEnabled = false

//设置scrollView是否支持点击状态栏回到顶部

scrollView.scrollsToTop = true

//scrollView的代理属性

scrollView.delegate = self

//设置scrollView最大最小缩放比例

scrollView.minimumZoomScale = 1.0

scrollView.maximumZoomScale = 3

let imageView = UIImageView(frame:CGRect(x: 0, y: 0, width: kScreenWidth - 40, height: kScreenHeight - 40))

imageView.tag = 200

imageView.image = UIImage(named: "a.jpg")

scrollView.addSubview(imageView)

self.view.addSubview(scrollView)

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

}

//在延展中管理UIScrollViewDelegate的协议方法extension ViewController : UIScrollViewDelegate{    //1 当ScorllView滚动的时候会持续触发    func scrollViewDidScroll(_ scrollView: UIScrollView) {        print("滚动着，滚动着")        print(scrollView.contentOffset)    }// any offset changes        //2  缩放过程中持续触发    func scrollViewDidZoom(_ scrollView: UIScrollView){            print("缩放着缩放着")        print(scrollView.zoomScale)    }// any zoom scale changes            // called on start of dragging (may require some time and or distance to move)    //3  开始拖拽的时候触发    func scrollViewWillBeginDragging(_ scrollView: UIScrollView){    print("开始拖拽了")            }        // called on finger up if the user dragged. velocity is in points/millisecond. targetContentOffset may be changed to adjust where the scroll view comes to rest    //4  将要结束拖拽的时候触发    func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer){

print("将要结束拖拽了")

}

// called on finger up if the user dragged. decelerate is true if it will continue moving afterwards

//5 已经结束拖拽的时候触发

func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool){

print("结束拖拽")

}

//6  将要开始减速的时候触发

func scrollViewWillBeginDecelerating(_ scrollView: UIScrollView){

print("将要开始减速")

}// called on finger up as we are moving

//7  减速完成，速度为零，这个方法很重要,往往都是在这个方法中获取ScorllView的contentOfSet

func scrollViewDidEndDecelerating(_ scrollView: UIScrollView){

print("减速完成")

} // called when scroll view grinds to a halt

//8  给ScorllView设置一个结束动画的时候会触发，不指定动画就不会触发

func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView){

} // called when setContentOffset/scrollRectVisible:animated: finishes. not called if not animating

//9  返回ScorllView上缩放的视图

func viewForZooming(in scrollView: UIScrollView) -> UIView? {

return scrollView.viewWithTag(200)

}// return a view that will be scaled. if delegate returns nil, nothing happens

//10 将要开始缩放的时候触发

func scrollViewWillBeginZooming(_ scrollView: UIScrollView, with view: UIView?){

print("将要开始缩放的时候触发")

} // called before the scroll view begins zooming its content

//11 结束缩放的时候触发

func scrollViewDidEndZooming(_ scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat){

print("结束缩放的时候触发")

} // scale between minimum and maximum. called after any 'bounce' animations

//12  设置点击状态栏是否能回到顶部

func scrollViewShouldScrollToTop(_ scrollView: UIScrollView) -> Bool {

return true

}// return a yes if you want to scroll to the top. if not defined, assumes YES

//13 scrollView回到顶部触发的方法

func scrollViewDidScrollToTop(_ scrollView: UIScrollView){

print("scrollView已经回到顶部")

} // called when scrolling

}