Switch from Synchronous request to Asynchronous request with image upload?

Question

I need some help, i have been searching around and cant find the correct answer im looking for.

I am uploading images and videos to my server via php, When im uploading the video or image, i want to be able to show a progress view, i have been told that the only way to do this is to use asynchronous instead of synchronous. I have been looking at ways to set up this, but cant really seem to find a good tutorial that will help me with what im trying to accomplish.

Here is some code:

- (void)post:(NSData *)fileData
{


NSMutableArray *array = [[NSMutableArray alloc]initWithContentsOfFile:[self saveUserLogin]];

int test;
NSString *string = [array objectAtIndex:3];
test = [string intValue];
test++;
NSData *videoData = fileData;
NSString *urlString = [[NSString alloc]initWithFormat:@"http://www.site.com/members/uploadMovie.php?&username=%@", [array objectAtIndex:0]];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:@"POST"];

NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
[request addValue:contentType forHTTPHeaderField:@"Content-Type"];

NSMutableData *body = [NSMutableData data];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
NSString *postName = [[NSString alloc]initWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; filename=\"vid%i.mov\"\r\n", test];
[body appendData:[[NSString stringWithString:postName] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:videoData]];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[request setHTTPBody:body];


NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];

NSLog(@"%@", returnString);

NSArray *values = [[NSArray alloc] initWithObjects: [array objectAtIndex:0],[array objectAtIndex:1], [array objectAtIndex:2], [NSString stringWithFormat:@"%i", test], nil];
[values writeToFile:[self saveUserLogin] atomically:YES];
[self.delegate didFinishController:self];
}

this is some code that im using to send a video. filedata is a paramater being passed in with the video data. I want to animate a UIProgressview for the upload progress. I have also heard that apple likes people to use asynchronous anyways. If someone could please help me set up asynchronous instead of what i have, i would be really grateful. Please be specific if you reply, like to what i need to import what delegates, methods. etc.

Thank you very much :)

EDIT:

This is what it looks like now:

- (void)post:(NSData *)fileData
{


NSMutableArray *array = [[NSMutableArray alloc]initWithContentsOfFile:[self saveUserLogin]];

int test;
NSString *string = [array objectAtIndex:3];
test = [string intValue];
test++;
NSData *videoData = fileData;
NSString *urlString = [[NSString alloc]initWithFormat:@"http://www.site.com/members/uploadMovie.php?&username=%@", [array objectAtIndex:0]];

NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL:[NSURL URLWithString:urlString] cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30];

NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", boundary];
[request addValue:contentType forHTTPHeaderField:@"Content-Type"];

NSMutableData *body = [NSMutableData data];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
NSString *postName = [[NSString alloc]initWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; filename=\"vid%i.mov\"\r\n", test];
[body appendData:[[NSString stringWithString:postName] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:videoData]];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[request setHTTPBody:body];


//NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
//NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
NSURLConnection *connection = [[NSURLConnection alloc]initWithRequest:request delegate:self];
if (connection) {
    NSLog(@"connected");
    responceData = [NSMutableData data];

}
else{
    NSLog(@"error");
}
//  NSLog(@"%@", returnString);

NSArray *values = [[NSArray alloc] initWithObjects: [array objectAtIndex:0],[array objectAtIndex:1], [array objectAtIndex:2], [NSString stringWithFormat:@"%i", test], nil];
[values writeToFile:[self saveUserLogin] atomically:YES];
   // [self.delegate didFinishController:self];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[responceData appendData:data];
}

- (void) connectionDidFinishLoading:(NSURLConnection *)connection {

NSString* responseString = [[NSString alloc] initWithData:responceData     encoding:NSUTF8StringEncoding];
NSLog(@"result: %@", responseString);

}

- (void) connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
NSLog(@"error - read error object for details");
}

Answer 1

NSUrlConnection has an asynchronous request with callbacks.

NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest   

NSUrlConnection overview:

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/URLLoadingSystem/Tasks/UsingNSURLConnection.html

That doc also points out you can get an estimation of upload progress by implementing a callback.

connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:

Estimating Upload Progress

You can estimate the progress of an HTTP POST upload with the connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite: delegate method. Note that this is not an exact measurement of upload progress, because the connection may fail or the connection may encounter an authentication challenge.