NSTimer

每隔一定时间执行某个函数

//创建定时器
//参数1.定时时间
//参数2.调用方法的对象
//参数3.定时时间到了自动调用的方法
//参数4.nil
//参数5.是否重复

NSTimer.scheduledTimerWithTimeInterval(0.3, target: self, selector: #selector(timmer), userInfo: nil, repeats: true)

实例：使用NSTimer实现帧动画

import UIKit
class ViewController: UIViewController {
var imageview = UIImageView()
override func viewDidLoad() {
    super.viewDidLoad()
    backImage()
    creatUI()
    //创建定时器
    //参数1.定时时间
    //参数2.调用方法的对象
    //参数3.定时时间到了自动调用的方法
    //参数4.nil
    //参数5.是否重复
    
    NSTimer.scheduledTimerWithTimeInterval(0.3, target: self, selector: #selector(timmer), userInfo: nil, repeats: true)

}
//MARK:定时器到时会调用的方法
func timmer() {
    //改变图片的位置
    //1.先拿到图片原来的位置
    let frame = imageview.frame
    imageview.frame = CGRectMake(frame.origin.x+10,frame.origin.y,121,96)
    if frame.origin.x>self.view.bounds.width {
        imageview.frame.origin.x = 0
    }
    
}

//MARK:创建界面
//背景图片
func backImage()  {
    let imageview1 = UIImageView.init(image: UIImage.init(named: "back2.jpg"))
    imageview1.frame = CGRectMake(0, 0, self.view.bounds.width, self.view.bounds.height)
    self.view.addSubview(imageview1)
}
//搭建页面
func creatUI() {
    imageview = UIImageView.init(image: UIImage.init(named: "DOVE 1"))
    imageview.frame = CGRectMake(30,300,121,96)
    self.view.addSubview(imageview)
    //设置动画数组
    var imageViewarr = [UIImage]()
    
    for i in 1...18{
         let image1 = UIImage.init(named: "DOVE \(i)")
        imageViewarr.append(image1!)
    }
    imageview.animationImages = imageViewarr
    imageview.animationDuration = 1
    imageview.animationRepeatCount = 0
    imageview.startAnimating()
   }
}