轮播图

import UIKit

let imageCount = 5

//屏幕的宽

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

//屏幕的高

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

class ViewController: UIViewController,UIScrollViewDelegate {

//定义一个定时器属性

var time:Timer!

lazy var scrollView : UIScrollView = {

let scr = UIScrollView(frame: UIScreen.main.bounds)

scr.contentSize = CGSize(width: CGFloat (imageCount) * kscreenWidth, height: kscreenHeight)

scr.isPagingEnabled = true

for i in 0..<imageCount{

let imageView = UIImageView(frame: CGRect(x: CGFloat(i) * kscreenWidth, y: 0, width: kscreenWidth, height: kscreenHeight))

imageView.image = UIImage(named:"\(i).jpg")

scr.addSubview(imageView)

}

//设置scrollView的偏移量

scr.contentOffset.x = kscreenWidth

//给scr设置代理

scr.delegate = self

return scr

}()

override func viewDidLoad() {

super.viewDidLoad()

// Do any additional setup after loading the view, typically from a nib.

//scrollView添加到父视图

self.view.addSubview(self.scrollView)

//添加定时器

self.time  =  Timer.scheduledTimer(timeInterval: 1.5, target: self, selector: #selector(timeAction), userInfo: nil, repeats: true)

}

//MARK:- 定时器的关联方法

func timeAction()  {

let page = self.scrollView.contentOffset.x / kscreenWidth

if page == 3.0 {

self.scrollView.contentOffset.x = kscreenWidth

}else{

self.scrollView.contentOffset.x += kscreenWidth

}

}

//MARK:- 开始拖拽的代理方法

func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {

//停止定时器的方法

self.time.invalidate()

//销毁定时器

self.time = nil

}

//MARK:- 结束拖拽的代理方法

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

//重新开启定时器

self.time = Timer.scheduledTimer(timeInterval: 1.5, target: self, selector: #selector(timeAction), userInfo: nil, repeats: true)

}

//scrollView减速完成触发的方法

func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {

let page = scrollView.contentOffset.x / kscreenWidth

if page == CGFloat (imageCount) - 1  {

scrollView.contentOffset.x = kscreenWidth

}else if page == 0{

scrollView.contentOffset.x = CGFloat(imageCount) - 2 * kscreenWidth

}

}

override func didReceiveMemoryWarning() {

super.didReceiveMemoryWarning()

// Dispose of any resources that can be recreated.

}

}