Question

我尝试使用NSURLSession在swift中下载文件：我的代表从未打过电话，我不知道为什么。有人可以帮忙吗？

代码：我的班级有以下协议：

class ViewController: UIViewController, NSURLSessionDelegate {

在我的课程中，我有一个下载zip功能：

func download_zip(sURL: String, sToLocation: String) {

    var delegate = self;
    delegate.storePath=sToLocation;
    delegate.progressView=progressView;
    struct SessionProperties {
        static let identifier : String! = "url_session_background_download"
    }
    var configuration = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(SessionProperties.identifier)
    var backgroundSession = NSURLSession(configuration: configuration, delegate: delegate, delegateQueue: nil)
    var url = NSURLRequest(URL: NSURL(string: sURL)!)
    var downloadTask = backgroundSession.downloadTaskWithRequest(url)
    downloadTask.resume()

}

在我的班级中我有一些代表职能：

//MARK: session delegate
func URLSession(session: NSURLSession, didBecomeInvalidWithError error: NSError?) {
    println("session error: \(error?.localizedDescription).")
}

func URLSession(session: NSURLSession, didReceiveChallenge challenge: NSURLAuthenticationChallenge, completionHandler: (NSURLSessionAuthChallengeDisposition, NSURLCredential!) -> Void) {
    completionHandler(NSURLSessionAuthChallengeDisposition.UseCredential, NSURLCredential(forTrust: challenge.protectionSpace.serverTrust))
}

func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location1: NSURL) {
    println("session \(session) has finished the download task \(downloadTask) of URL \(location1).")


}

func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
    println("session \(session) download task \(downloadTask) wrote an additional \(bytesWritten) bytes (total \(totalBytesWritten) bytes) out of an expected \(totalBytesExpectedToWrite) bytes.")


}

func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didResumeAtOffset fileOffset: Int64, expectedTotalBytes: Int64) {
    println("session \(session) download task \(downloadTask) resumed at offset \(fileOffset) bytes out of an expected \(expectedTotalBytes) bytes.")
}

func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
    if error == nil {
        println("session \(session) download completed")
    } else {
        println("session \(session) download failed with error \(error?.localizedDescription)")
    }
}

func URLSessionDidFinishEventsForBackgroundURLSession(session: NSURLSession) {
    println("background session \(session) finished events.")

    if !session.configuration.identifier.isEmpty {
        callCompletionHandlerForSession(session.configuration.identifier)
    }
}

//MARK: completion handler
func addCompletionHandler(handler: CompleteHandlerBlock, identifier: String) {
    handlerQueue[identifier] = handler
}

func callCompletionHandlerForSession(identifier: String!) {
    var handler : CompleteHandlerBlock = handlerQueue[identifier]!
    handlerQueue!.removeValueForKey(identifier)
    handler()
}

没有调用委托函数。有没有人看到这个问题？

Answer 1

你有：

var backgroundSession = NSURLSession(configuration: configuration, delegate: delegate, delegateQueue: nil)

应该是：

var backgroundSession = NSURLSession(configuration: configuration, delegate: self, delegateQueue: NSOperationQueue.mainQueue())

代表必须自我设定。还要在协议中添加“NSURLSessionDataDelegate”。

Answer 2

尝试将NSURLSession存储到属性中，我认为您的会话可能会被ARC从内存中清除

使用NSURLSession下载代表（IOS，swift）

2 个答案: