Swift 系统学习 34 线程通信 Swift3.0 子线程下载图片主线程显示图片

import UIKit

class ViewController: UIViewController {

var imageView: UIImageView!

override func viewDidLoad() {
super.viewDidLoad()

imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
self.view.addSubview(imageView)
// Do any additional setup after loading the view, typically from a nib.

// 程序启动后开子线程下载图片,图片下载完成之后回到主线程设置图片
Thread.detachNewThreadSelector(#selector(ViewController.downloadImage), toTarget: self, with: nil)

}

func downloadImage() {
// 获得要下载图片的url
let url = NSURL.init(string: "http://cdn.cocimg.com/assets/images/logo.png")
// 把url地址指向资源的二进制下载到本地
let imageData = NSData.init(contentsOf: url! as URL)
// 把二进制数据转换为图片
let image = UIImage.init(data: imageData! as Data)

// 打印查看当前线程(应该是在子线程中下载图片)
print("当前线程为\(Thread.current)")

// 线程间通信
self.performSelector(onMainThread: #selector(ViewController.showImage), with: image, waitUntilDone:true)

}

func showImage(image:UIImage) {
imageView.image = image
print("处理UI刷新操作的线程:\(Thread.current)")
}

override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}

}