ios - 我如何调用这个复杂的 NSURLSession？

Question

我知道这是我想要的方法，使用 didFinishDownloadingToURL，但是，我是 swift 的新手，不清楚如何调用这个方法。你能举个例子吗？谢谢。

class DownloadDelegate : NSObject, NSURLSessionDownloadDelegate {
    func URLSession(session: NSURLSession,
        downloadTask:NSURLSessionDownloadTask,
        didFinishDownloadingToURL location: NSURL) {
            println("YO")
    }
}

Answer 1

一个简单的例子

class DemoDownloadClass: NSObject,NSURLSessionDelegate,NSURLSessionDownloadDelegate {
var session:NSURLSession?
var downloadUrl:String
var completion:(NSURL)->()
init(url:String,completionBlock:(location:NSURL)->()){
    completion = completionBlock
    downloadUrl = url
    super.init()
    session = NSURLSession(configuration: NSURLSessionConfiguration.defaultSessionConfiguration(), delegate: self, delegateQueue: nil)
}
func start(){
    let request = NSURLRequest(URL: NSURL(string: downloadUrl)!);
    let downloadTask = session!.downloadTaskWithRequest(request)
    downloadTask.resume()
}
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) {
    completion(location)
}
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
    //here get progress
}
}

然后怎么用

class DemoTableController: UIViewController{
var test:DemoDownloadClass?
override func viewDidLoad() {
    test = DemoDownloadClass(url: "yoururl", completionBlock: { (location) -> () in
        //Use location to get file,I did not handle error here.Just as an exmaple
    })
    test?.start()
}
}