urlSession:dataTask:didReceive:completionHandler 未在 Xcode8 Swift3 中调用

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【中文标题】urlSession:dataTask:didReceive:completionHandler 未在 Xcode8 Swift3 中调用【英文标题】:urlSession:dataTask:didReceive:completionHandler not called in Xcode8 Swift3 【发布时间】:2016-11-02 11:26:22 【问题描述】:

我使用以下代码创建了一个背景 URLSession 对象:

let identifier = /* some background identifier */
let config = URLSessionConfiguration.background(withIdentifier: identifier)
self.session = URLSession(configuration: config, delegate: self, delegateQueue: nil)

我还在委托类中实现了以下URLSessionDataDelegate 方法:

public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: @escaping (URLSession.ResponseDisposition) -> Void) 
    // code goes here


public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) 
    // code goes here


public func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?)  
    // code goes here

我可以使用以下方法从该会话中成功调用 URLSessionUploadTask

let fileURl = /* some file url */
let request = /* some URLRequest */
let task = session.uploadTask(with: request, fromFile: fileUrl)
task.resume()

但由于某种原因,我只收到以下回调:

`urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?)` 

`urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data)`.

委托方法:

`urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: @escaping (URLSession.ResponseDisposition) -> Void)`

永远不会被调用。

这是 Xcode8 中的错误还是我遗漏了一些重要的东西? 感谢您的帮助!

【问题讨论】:

它是一个工作代码并且在早期的 xcode 中工作正常吗? 当我在其他两个委托方法上获得委托回调时,代码可以正常工作,我无法在早期的 Xcode 中对此进行测试,因为它们不支持 Swift 3。 【参考方案1】:

Apple SDK 直接引用此方法:

/*
 * Messages related to the operation of a task that delivers data
 * directly to the delegate.
 */
@protocol NSURLSessionDataDelegate <NSURLSessionTaskDelegate>
@optional
/* The task has received a response and no further messages will be
 * received until the completion block is called. The disposition
 * allows you to cancel a request or to turn a data task into a
 * download task. This delegate message is optional - if you do not
 * implement it, you can get the response as a property of the task.
 *
 * This method will not be called for background upload tasks (which cannot be converted to download tasks).
 */
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
                                 didReceiveResponse:(NSURLResponse *)response
                                  completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler;

编辑:为引用添加更多上下文

【讨论】:

您能否提供此直接报价的链接? 更新了我的答案 有趣的是,此信息仅显示在 Obj-C 文档中,而不显示在 Swift 文档中。我会用苹果标记它。非常感谢,匿名的!

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