Uploading Files from iPhone

We recently completed an iPhone application that allows user to, among other things, perform voice-recording and upload the recorded file to a server. For uploading, it uses HTTP multipart POST against an Apache webserver. This type of arrangement is a very common way of sending a file to a webserver. I am certain that similar implementations can be found in several different programming languages. Here is my Objective C implementation...I tried to focus on brevity and encapsulation.

The code:

/**

 * Upload a file to a webserver thru http post.

 * uid is the http request id

 * requestData is list of key/value pairs to be sent along with the file

 * url is the destination url

 * filePath is absolute file path of the file to be uploaded

 */

- (void)postUpload:(NSString *)url

  :(NSString *)uid

  :(NSDictionary *)requestData

  :(NSString *)filePath

{

NSURL *theURL = [NSURL URLWithString:url];

NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:theURL 

     cachePolicy:NSURLRequestReloadIgnoringCacheData 

 timeoutInterval:20.0f];

[theRequest setHTTPMethod:@"POST"];

[theRequest setValue:uid forHTTPHeaderField:@"uid"];

// define post boundary...

NSString *boundary = [[NSProcessInfo processInfo] globallyUniqueString];

NSString *boundaryString = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];

[theRequest addValue:boundaryString forHTTPHeaderField:@"Content-Type"];

// define boundary separator...

NSString *boundarySeparator = [NSString stringWithFormat:@"--%@\r\n", boundary];

//adding the body...

NSMutableData *postBody = [NSMutableData data];

// adding params...

for (id key in requestData) {

NSString *formDataName = [NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", key];

NSString *formDataValue = [NSString stringWithFormat:@"%@\r\n", [requestData objectForKey:key]];

[postBody appendData:[boundarySeparator dataUsingEncoding:NSUTF8StringEncoding]];

[postBody appendData:[formDataName dataUsingEncoding:NSUTF8StringEncoding]];

[postBody appendData:[formDataValue dataUsingEncoding:NSUTF8StringEncoding]];

}

// if file is defined, upload it...

if (filePath) {

NSArray *split = [filePath componentsSeparatedByString:@"/"];

NSString *fileName = (NSString*)[split lastObject];

NSData *fileContent = [NSData dataWithContentsOfFile:filePath options:0 error:nil];

[postBody appendData:[boundarySeparator dataUsingEncoding:NSUTF8StringEncoding]];

[postBody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"audioBody\"; filename=\"%@\"\r\n", fileName] dataUsingEncoding:NSUTF8StringEncoding]];

[postBody appendData:[@"Content-Type: application/octet-stream\r\n\r\n"

dataUsingEncoding:NSUTF8StringEncoding]];

[postBody appendData:fileContent];

}

[postBody appendData:[[NSString stringWithFormat:@"\r\n--%@--\r \n",boundary]

dataUsingEncoding:NSUTF8StringEncoding]];

[theRequest setHTTPBody:postBody];

NSURLResponse *theResponse = NULL;

NSError *theError = NULL;

NSData *reqResults = [NSURLConnection sendSynchronousRequest:theRequest

  returningResponse:&theResponse

  error:&theError];

if (!reqResults) {

NSLog(@"Connection error for URL: %@", [url description]);

UIAlertView *alert = [UIAlertView alloc];

[[alert initWithTitle:@"Error in connection"

  message:[theError localizedDescription]

delegate:self

cancelButtonTitle:nil

otherButtonTitles:@"Quit", nil] autorelease];

[alert show];

}

}

Here's an example of how you can use this method:

NSArray *keys = [NSArray arrayWithObjects:@"recipients", @"title", @"textBody", nil];

NSArray *objects = [NSArray arrayWithObjects:uids, inputSubject.text, inputMessage.text, nil];

NSDictionary* postData = [NSDictionary dictionaryWithObjects:objects forKeys:keys];

// post now...

[[WebService alloc] postUpload:URL_ENDPOINT_SEND_MESSAGE

  :appDelegate.uid

  :postData

  :[recorder recordFilePath]];

URL_ENDPOINT_SEND_MESSAGE is set to the URL that can receive a multipart POST. To test this out, I have quickly written the following PHP code. 

<?php

define('FILE_SAVE_DIRECTORY','/folder/to/save/uploaded/files/');

error_log("Requesting upload file....");

error_log(print_r($_SERVER, true));

error_log("\n\n");

error_log(print_r($_FILES, true));

if($_POST && isset($_FILES['file'])) {

error_log("  the file:...." . $_FILES['file']['name']);

$file = $_FILES['file'];

$dst = FILE_SAVE_DIRECTORY . basename($file['name']);

if (move_uploaded_file($file['tmp_name'], $dst)){

echo 'Upload Successfully: '.$dst;

}

else {

echo 'Error uploading the file.';

}

}

?>

Put this code in your php-enabled webserver. Then, set URL_ENDPOINT_SEND_MESSAGE to point to the script.

It's that simple. Now you're ready to use HTTP upload in your next iPhone project.

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