8.25 ScrollView 滚动视图

用途非常广泛，基本上能滚动的都是ScrollView，网页，QQ，微信等......

import UIKit

class ViewController: UIViewController, UIScrollViewDelegate {
    var scrollView: UIScrollView!
    var pageControl: UIPageControl!
    var redView: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        //UIScrollView
//        let textView = UITextView(frame: CGRect(x: 100, y: 100, width: 200, height: 100))
//        textView.backgroundColor = UIColor.redColor()
//        self.view.addSubview(textView)
        
        //1. 滚动
        //2. 缩放
        scrollView = UIScrollView()
        scrollView.frame = CGRectMake(0, 100, self.view.bounds.size.width, 200)
        scrollView.backgroundColor = UIColor.cyanColor()
        self.view.addSubview(scrollView)
        
        redView = UIView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
        redView.backgroundColor = UIColor.redColor()
        
        scrollView.addSubview(redView)
        
        let greenView = UIView(frame: CGRect(x: scrollView.frame.size.width - 50, y: scrollView.frame.size.height - 50, width: 50, height: 50))
        greenView.backgroundColor = UIColor.greenColor()
        scrollView.addSubview(greenView)
        
        //UIScrollView能否滚动
        //1. scrollEnabled
        //2. contentSize: (0, 0) 内容大小，只有当内容尺寸超过本身尺寸时才滚动
//        print(scrollView.scrollEnabled)
        scrollView.contentSize = CGSize(width: scrollView.frame.size.width * 3, height: scrollView.frame.size.height)
        scrollView.pagingEnabled = true
        scrollView.delegate = self
        
//        缩放
        scrollView.maximumZoomScale = 10
        scrollView.minimumZoomScale = 0.5
//        scrollView.contentInset = UIEdgeInsets(top: 10, left: 0, bottom: 10, right: 0)
        //向左/向上滚动：正方向
//        scrollView.contentOffset = CGPoint(x: -100, y: 0)
        
        //一次只允许一个方向滚动
//        scrollView.directionalLockEnabled = true
        //弹性效果
//        scrollView.bounces = false
        
//        禁止滚动回弹效果
//        scrollView.showsHorizontalScrollIndicator = false
//        scrollView.showsVerticalScrollIndicator = false
        
        //小点处于控件中央
        pageControl = UIPageControl(frame: CGRect(x: 0, y: scrollView.frame.origin.y + scrollView.frame.size.height - 20, width: scrollView.frame.size.width, height: 20))
        pageControl.numberOfPages = 3
        pageControl.currentPageIndicatorTintColor = UIColor.blueColor() //当前页蓝色小点
        pageControl.pageIndicatorTintColor = UIColor.yellowColor()  //其他页黄色小点
        pageControl.addTarget(self, action: #selector(didClicked(_:)), forControlEvents: .ValueChanged)
        self.view.addSubview(pageControl)
    }
    
    func didClicked(sender: UIPageControl) {
        print(sender.currentPage)
//        scrollView.contentOffset = CGPoint(x: scrollView.bounds.size.width * CGFloat(sender.currentPage), y: 0)
        
        let offset = CGPoint(x: scrollView.bounds.size.width * CGFloat(sender.currentPage), y: 0)
//        scrollView.setContentOffset(offset, animated: true)
        
        let rect = CGRect(x: offset.x, y: 0, width: scrollView.bounds.size.width, height: scrollView.bounds.size.height)
        scrollView.scrollRectToVisible(rect, animated: true)
    }
    
    func scrollViewDidScroll(scrollView: UIScrollView) {
        //1. 只要有位移就会持续调用
        print(scrollView.contentOffset)
    }
    
    func scrollViewWillBeginDragging(scrollView: UIScrollView) {
        print("begin dragging 开始拖动")
    }
//    点击拖动，停下后才松开，则调用"结束拖动"，如果在拖动过程中松开，则调用"减速" 
    func scrollViewWillEndDragging(scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
        print("结束拖动")
    }
    
    func scrollViewDidEndDragging(scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if decelerate {
            print("开始减速")
        }
        else {
            print("无需减速")
            pageControl.currentPage = Int(scrollView.contentOffset.x / scrollView.bounds.size.width)
        }
    }
    
    func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
        print("停止减速")
        pageControl.currentPage = Int(scrollView.contentOffset.x / scrollView.bounds.size.width)
    }
    
    func changePage() {
        
    }
    
    func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
        return redView
    }
}

编译运行结果如下：

Paste_Image.png

双手开合实现缩放：

Paste_Image.png

可以试着把图片加入到里面，图片设置的位置加在ScrollView上，宽高和ScrollView一样。