Xcode - อยากรู้ว่าถ้าจะเขียนแบบ AsyncTask เหมือน Android ต้องเขียนแบบไหนครับ??

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
    
    [UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
    
    NSURLRequest *theRequest =
    [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.thaicreate.com/url/getGallery.php"]
                     cachePolicy:NSURLRequestReloadIgnoringLocalCacheData
                 timeoutInterval:10.0];
    
    NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
    
    // Loading Show Alert View...
    loading = [[UIAlertView alloc] initWithTitle:@"" message:@"Please Wait..." delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];
    UIActivityIndicatorView *progress= [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(125, 50, 30, 30)];
    progress.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;
    [loading addSubview:progress];
    [progress startAnimating];
    [progress release];
    [loading show];
    

}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    receivedData = [[NSMutableData alloc] init];
}

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

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    if(receivedData)
    {
	// Hide Alert View
        [UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
        [loading dismissWithClickedButtonIndex:0 animated:YES];
    }
}