How can I pass a "C++ completion handler" to NSURLSessionDataTask to process the data it returned?

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Our application is written mostly in C++, the core of which is static library shared by multiple platforms (Win, Mac, Android, iOS).

We're adding iOS support, and have a series of functions that use libcurl that perform all of the HTTP get/post communication with our servers.

But for iOS, we're now implementing those calls using NSURLSession.

My question is pretty simple, how does the code look like to provide a C++ completionHandler to NSURLSessionDataTask?

Perhaps I'm thinking about this the wrong way, but that is the clearest I can think to make the question.

Using example code out in the world, I tried the following, to no avail. The Objective-C++ code inside the completion handler never gets called. It returns to the C++ code and never returns.

This is the objective-C++ function:

std::string get(std::string urlStr)
{
    NSURLSession *defaultSession = [NSURLSession sharedSession];

    NSURL * url = [NSURL URLWithString:[NSString stringWithUTF8String:urlStr.c_str()]];

    __block std::string returnVal;

    NSURLSessionDataTask * dataTask = [defaultSession dataTaskWithURL:url
                                                         completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if(error == nil)
        {
            NSString * text = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
            NSLog(@"Data = %@",text);

            returnVal = std::string([text UTF8String]);
        }

    }];

    [dataTask resume];

    return returnVal;
}

And this is how I invoke that code in the C++:

    response = get(url);
    fprintf(stderr, "Data in C++: %s", response.c_str());

asked 1 min ago

A. G.

1

How can I pass a "C++ completion handler" to NSURLSessionDataTask to process the data it returned?