IOS Operation实现多线程

 1 var topImageView = UIImageView()
 2 var footImageView = UIImageView()
 3 override func viewDidLoad() {
 4 super.viewDidLoad()
 5 // Do any additional setup after loading the view,
 typically from a nib.
 6 topImageView = UIImageView(frame：CGRect(x：0,
 y：0, width：320, height：280))
 7 self.view.addSubview(topImageView)
 8
 9 footImageView = UIImageView(frame：CGRect(x：0,
 y：280, width：320, height：290))
 10 self.view.addSubview(footImageView)
 11
 12 let downloadA = getOperation(name：”下载线程 A”,
 imageUrl：
 “http：//images.apple.com/v/watch/k/images/overview/watch_03_large.jpg”,
 isTopOne：true)
 13
 14 let downloadB = getOperation(name：”下载线程B”,
 imageUrl：“http：//images.apple.com/v/watch/k/images/overview/watch_05_large.jpg”,
 isTopOne：false)
 15
 16 let queue = OperationQueue()
 17 queue.maxConcurrentOperationCount = 1
 18 queue.addOperation(downloadA)
 19 queue.addOperation(downloadB)
 20
 21 for operation in queue.operations{
 22 print(“Operation名称：”+operation.name！)
 23 }
 24 }
 25 func getOperation(name：String, imageUrl：String,
 isTopOne：Bool) -> BlockOperation{
 26 let download = BlockOperation(block：{_ in
 27 let url = URL(string：imageUrl)
 28 var data：Data！
 29 do{
 30 Thread.sleep(forTimeInterval：1.0)
 31 try data = Data(contentsOf：url！)
 32 let image = UIImage(data：data)
 33 if isTopOne{
 34 self.perform(#selector(ViewController.showTopImage),
 on：Thread.main, with： image, waitUntilDone：true)
 35 }
 36 else{
 37
 self.perform(#selector(ViewController.showFootImage), on：
 Thread.main, with： image, waitUntilDone：true)
 38 }
 39 }catch{
 40 print(“下载图片失败。”)
 41 }
 42 })
 43 download.name = name
 44 return download
 45 }
 46 func showTopImage(image：UIImage){
 47 self.topImageView.image = image
 48 }
 49
 50 func showFootImage(image：UIImage){
 51 self.footImageView.image = image
 52 }