Uploading file using NSURLSessionUploadTask to PHP

I have a video upload system in an iOS app using NSURLSessionUploadTask. The video file is saved to an NSURL so I am using the following code in my upload method:

request.HTTPMethod = @"POST";
[request addValue:@"file" forHTTPHeaderField:@"fileName"];

// Create upload task
NSURLSessionUploadTask *task = [session uploadTaskWithRequest:request fromFile:filePath completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    if(!error) {
        // handle success
    } else {
        // handle error
    }
}];

// Run the task
[task resume];

I have a PHP server (using Laravel) running under nginx to handle this upload. I have tested it with Postman, and it accepts uploads fine (expecting a file under the name "file").

When I run the above objc code, the server tells me that no file has been uploaded (the $_FILES array is empty).

I have tried with and without setting the "fileName" header, and I've tried setting "Content-Type" to "multipart/form-data" but none of these works.

How can I get NSURLSessionUploadTask to properly upload these files (from an NSURL) to the server?

This post seems to detail a similar problem: NSURLSessionUploadTask not passing file to php script

When using NSURLSessionUploadTask [uploadTaskWithRequest: fromFile:], the file is sent in the request body as binary.

To save that file in PHP you can simply get the request body and save it to file.

Obviously, it is best to do some sort of file format validation.

Objective-C Code:

// Define the Paths
NSURL *URL = [NSURL URLWithString:kDestinationURL];

// Create the Request
NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:URL];
[request setHTTPMethod:@"POST"];

// Configure the NSURL Session
NSURLSessionConfiguration *config = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"com.upload"];
config.HTTPMaximumConnectionsPerHost = 1;
NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:nil];

// Define the Upload task
NSURLSessionUploadTask *uploadTask = [session uploadTaskWithRequest:request fromFile:audioRecorder.url];

// Run it!
[uploadTask resume];

PHP Code:

<?php
    // File Path to save file
    $file = 'uploads/recording.m4v';

    // Get the Request body
    $request_body = @file_get_contents('php://input');

    // Get some information on the file
    $file_info = new finfo(FILEINFO_MIME);

    // Extract the mime type
    $mime_type = $file_info->buffer($request_body);

    // Logic to deal with the type returned
    switch($mime_type) 
    {
        case "video/mp4; charset=binary":

            // Write the request body to file
            file_put_contents($file, $request_body);

            break;

        default:
            // Handle wrong file type here
    }
?>

I wrote a code example of recording audio and uploading it to a server here: https://github.com/gingofthesouth/Audio-Recording-Playback-and-Upload

I hope that helps.