setbackground loading with do while loop

Question

i am working on an application where i check for url using following code.

-(void)exists
{
    NSString *strImg = @"some url";


    NSURL *aImgUrl = [NSURL URLWithString:strImg];

    NSMutableURLRequest *imgRequest = [NSMutableURLRequest requestWithURL:strImg];
    [imgRequest setHTTPMethod:@"HEAD"];

    imgConnection = [NSURLConnection connectionWithRequest:imgRequest delegate:self];
}

This is what i do when i get response.

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{

    if ([(NSHTTPURLResponse *)response statusCode] == 200)
    {
        // url exists
        appDel.isExists = TRUE;
        temp = FALSE;
        [self loadData];
        NSLog(@"%ld",(long)[(NSHTTPURLResponse *)response statusCode]);
    }
    else if([(NSHTTPURLResponse*)response statusCode] == 404)
    {
        //url does not exists
        appDel.isExists = FALSE;
        temp = TRUE;
        [self loadData];
        NSLog(@"%ld",(long)[(NSHTTPURLResponse *)response statusCode]);
    }
}

This is my load data code

-(void)loadData
{


    result = FALSE;

    isReqSent = FALSE;

    do
    {
        if (appDel.isExists == TRUE)
        { 
            NSURL *aTxtUrl = [NSURL URLWithString:apiText];
            NSURL *aImgUrl = [NSURL URLWithString:apiImage];

            NSURLRequest *imgRequest = [NSURLRequest requestWithURL:aImgUrl];
            NSURLRequest *txtRequest = [NSURLRequest requestWithURL:aTxtUrl];

           [NSURLConnection sendAsynchronousRequest:txtRequest queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError)
             {
                 if (data)
                 {
                         NSString *strTxt = [[NSString alloc]initWithData:data encoding:NSUTF8StringEncoding];
                         [lblTime setText:strTxt];
                          [policyImgWebView loadRequest:imgRequest];

                         result = TRUE;                     
                 }

             }];

        }

        if (result)
        {
            appDel.isExists = TRUE;
        }
        else
        {
            if(!isReqSent)
            {
                NSString *soapMessage = @"my soap message";

                NSString *soapAction = @"my soap url";


                [objWebServiceParser xmlParsing:soapMessage :soapAction :Number];
                isReqSent = TRUE;
            }

            }
        if (temp)
        {
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
                [self backgroundProcess];
            });
        }

    } while (result == FALSE);

This is my background Process

-(void)backgroundProcess
{

    NSString *strImg = @"some url";

    NSURL *aImgUrl = [NSURL URLWithString:apiImage];

    NSMutableURLRequest *imgRequest = [NSMutableURLRequest requestWithURL:aImgUrl];
    [imgRequest setHTTPMethod:@"HEAD"];

    imgConnection = [NSURLConnection connectionWithRequest:imgRequest delegate:self];

}

i do not know where i am doing wrong, can any one guide me?

i want background process to keep running until it gets data, when data received appdel.isExists gets true & gets on main thread to update ui.

I tried GCD & performSelectorInTheBackground but i am not getting it right & i get NSThread fail error 35.

---

It worked with NSURLSessionDownloadTask but still looking for better option.

Answer 1

Don't call NSURLConnection in background. As NSURLConnection will work automatically. As you are not sending asynchronous request it will work in background and won't hang your main thread. In your load data remove dispatch. You have:

if (temp)
    {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
            [self backgroundProcess];
        });
    }

make it:

if (temp)
    {
        [self backgroundProcess];
    }

You don't need to use dispatch.