Download File In Background

A Quick & Simple Method

Get file

	//Get file on a background thread to stop GUI locking up
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData* data = [NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://mydomain.com/comefile.php"]];
        [self performSelectorOnMainThread:@selector(fetchedData:)
							   withObject:data waitUntilDone:YES];
    });

 

File Received

//***********************************
//***********************************
//********** FILE RECEIVED **********
//***********************************
//***********************************
- (void)fetchedData:(NSData *)responseData
{

}

 

A Fuller Featured Method

In your .h header file

@interface ###
{
	NSMutableData *fileData;
	NSURLConnection *connectionInProgress;
}

- (void)DownloadFileFromUrl:(NSString *)fileURL;

In Your .m file

//********************************************
//********************************************
//********** DOWNLOAD FILE FROM URL **********
//********************************************
//********************************************
- (void)DownloadFileFromUrl:(NSString *)fileURL
{

	NSLog(@"Get file from URL starting");

	NSURL *url = [NSURL URLWithString:fileURL];
	NSURLRequest *request = [NSURLRequest requestWithURL:url
											 cachePolicy:NSURLRequestReloadIgnoringCacheData
										 timeoutInterval:30];

	//Clear any existing connection if there is one
	if (connectionInProgress)
	{
		[connectionInProgress cancel];
		[connectionInProgress release];
	}

	[fileData release];
	fileData = [[NSMutableData alloc] init];

	connectionInProgress = [[NSURLConnection alloc] initWithRequest:request
														   delegate:self
												   startImmediately:YES];
}

//*************************************************
//*************************************************
//********** NEXT BLOCK OF DATA RECEIVED **********
//*************************************************
//*************************************************
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
	[fileData appendData:data];
}

//******************************************
//******************************************
//********** ALL OF DATA RECEIVED **********
//******************************************
//******************************************
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
	NSLog(@"Got file from URL");

	//CONVERT TEXT FILE TO STRING
	//NSString *SourceString = [[[NSString alloc] initWithData:fileData encoding:NSUTF8StringEncoding] autorelease];
	//NSLog(@"Text file received. Contents = %@", s);

	//DISPLAY AN IMAGE FILE
	//[MyImageView setImage:[UIImage imageWithData:fileData]];

	//RELEASE CONECTION
	if (connectionInProgress)
	{
		[connectionInProgress release];
		connectionInProgress = nil;
	}
}

//***************************************
//***************************************
//********** CONNECTION FAILED **********
//***************************************
//***************************************
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
	[connectionInProgress release];
	connectionInProgress = nil;

	[fileData release];	
	fileData = nil;

	NSLog(@"Get file from URL failed");
}
//*****************************
//*****************************
//********** DEALLOC **********
//*****************************
//*****************************
- (void)dealloc
{
	[fileData release];
	[connectionInProgress release];

	[super dealloc];
}