第二周第三天 轮播图

轮播图

1,往工程梨添加几张图片

• 在工程程序添加三个全局变量

import UIKit

class ViewController: UIViewController,UIScrollViewDelegate {
    var scrollerView : UIScrollView! = nil
    var pagec:UIPageControl! = nil
    var timer:Timer! = nil

• 1.在viewDidload.swift先定义滑动条
• 2.往工程添加几张图片
• 3.选中滑块，几个手指滑和滑动多少下。添加到视图上。
• 4.定义一个timer，触发点击事件，添加一个方法。在方法里面获取当前的偏移量，如果到第四个要自动跳到第一个
• 5.timer的方法，开始拖拽的方法，结束拖拽的方法，滚动条的方法，协议的方法，滑动会执行的方法
• 6//根据偏移量定位到第几个点

import UIKit

class ViewController: UIViewController,UIScrollViewDelegate {
    var scrollerView : UIScrollView! = nil
    var pagec:UIPageControl! = nil
    var timer:Timer! = nil

    override func viewDidLoad() {
        super.viewDidLoad()
        let src = UIScrollView(frame: CGRect(x: 0, y: 100, width: self.view.frame.size.width, height: 300))
        self.view.addSubview(src)
        src.contentSize = CGSize(width: self.view.frame.size.width * 5, height: 300)

        //加图片
        for index in 1...5{
            let name = "\(index).jpg"
            let image = UIImage(named: name)
            let x = CGFloat(index-1)*self.view.frame.size.width
            let imageV = UIImageView(frame: CGRect(x: x, y: 0, width: self.view.frame.size.width, height: 300.0))
            scrollerView = src
            src.delegate = self
            imageV.image = image
            src.addSubview(imageV)
            
        
        }
        
        
        //UIPageControl
        let page = UIPageControl(frame: CGRect(x: 100, y: 250, width: self.view.frame.size.width-200, height: 280))
        self.pagec = page
        page.numberOfPages = 4
        page.currentPage = 0
        page.addTarget(self, action: #selector(pageAction), for: .valueChanged)
        // 没选中滑块的颜色
        page.pageIndicatorTintColor = UIColor.red
        //选中滑块的颜色
        page.currentPageIndicatorTintColor = UIColor.green
      self.view.addSubview(page)
        //timer
        self.timer = Timer.scheduledTimer(timeInterval:1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
        self.timer.fire()
   }
    func timerAction(){
        //获取到当前的offest
        let offset = self.scrollerView.contentOffset
        let width = self.view.frame.size.width
        // scrollerView进行滚动
        scrollerView.setContentOffset(CGPoint(x:offset.x+width,y:offset.y), animated: true)
        
        //让当前的offest.x+width,如果到第四个要跳到第一个
        if scrollerView.contentOffset.x >= width * 4 {
            let point = CGPoint(x: 0, y: 0)
            scrollerView.contentOffset = point
        }
        
    }
    //开始拖拽
    func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
        self.timer.invalidate()
        self.timer = nil
        
    }
    //结束拖拽
    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        self.timer = Timer.scheduledTimer(timeInterval:1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
        //self.timer.fire()
        //一秒之后再执行
         let time =  DispatchTime.now() + 1.0
        DispatchQueue.main.asyncAfter(deadline:time){
            if let _ = self.timer{
                self.timer.fire()
            }
           
    }
    }
    
    func pageAction(page:UIPageControl){
        
        let index = page.currentPage
        let point = CGPoint(x:CGFloat(index) * self.view.frame.size.width, y: 0)
        //修改偏移量
       self.scrollerView.setContentOffset(point, animated: true)
        
    }
    //协议的方法，滑动会执行的方法
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        //获取到偏移量
        let x = scrollerView.contentOffset.x
        let width = self.view.frame.size.width
        if (x >= width * 4) {
            self.pagec.currentPage = 0
        }else
        {
            self.pagec.currentPage = Int(x/width)
        }
        
        
        //根据偏移量定位到第几个点
//        switch x {
//        case 0:
//            self.pagec.currentPage = 0
//      
//        case 1 * width:
//            self.pagec.currentPage = 1
//       
//        case 2 * width:
//            self.pagec.currentPage = 2
//         
//        case 3 * width:
//            self.pagec.currentPage = 3
//
//        default:
//            print("other")
//        }
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}