NSURLSessionTaskDelegate method URLSession: task: didCompleteWithError: never called

Question

All of my network code relies on NSURLSession delegate methods, not termination handlers. My data and download tasks work fine, but my download tasks never result in URLSession:task:didCompleteWithError:. However URLSession:dataTask:didReceiveData:, the URLSession:dataTask:willCacheResponse:completionHandler:delegate methods are also ARE .

If I set the resource timeout to a really low value for my session object, it didCompleteWithErrorsis called, but this is clearly not a solution.

Any ideas? I'm going to go crazy.

Thank.

Answer 1

didCompleteWithError, willCacheResponse, completionHandler. completionHandler.

NSURLSession, completionHandler (, , ..). , , completionHandler.

Answer 2

. - - ​​ - , NSURLSessionTaskDelegate . .

NSURLSession ; completionHandler .

:

func dataTaskWithRequest(_ request: NSURLRequest) -> NSURLSessionDataTask

func dataTaskWithRequest(_ request: NSURLRequest, completionHandler completionHandler: (NSData?, NSURLResponse?, NSError?) -> Void) -> NSURLSessionDataTask

completionHandler, - NSURLSessionTaskDelegate . , NSURLSession.

. task, :

import UIKit
import XCPlayground

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true


class MyDelegate:NSObject, NSURLSessionTaskDelegate
{
    func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
        NSLog("Delegate called")
    }
}


let myDel = MyDelegate()
let config = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: config, delegate: myDel, delegateQueue: NSOperationQueue())
let url = NSURL(string: "http://httpbin.org")
let request: NSURLRequest = NSURLRequest(URL: url!)

// With completionHandler, delegate method above NOT called
let task : NSURLSessionDataTask = session.dataTaskWithRequest(request, completionHandler: {(data, response, error) in
        NSLog("Task done")
})

// Without completionHandler, delegate method above IS called
//let task : NSURLSessionDataTask = session.dataTaskWithRequest(request)

task.resume()

TL;DR: , , NSURLSession ? ; , Handler.

Answer 3

, NSURLSession , .

API, API NSURLSession . , , :

• , , .

• .

:

NSURLSession Handler

Answer 4

completionHandler willCacheResponse, .

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask willCacheResponse:(NSCachedURLResponse *)proposedResponse completionHandler:(void (^)(NSCachedURLResponse *__nullable cachedResponse))completionHandler {

    NSLog(@"%s", __FUNCTION__);
    completionHandler(proposedResponse);
}