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.

Yes when i process to background i do not get response in NSURLConnection Delegate Methods. — Jaymin Raval
yes @AkshitZaveri but in background (keep checking until url is valid, as soon as it`s valid load it) — Jaymin Raval

Akshit Zaveri Akshit Zaveri · Accepted Answer · 2014-02-28T03:21:56

To load the image in your UIImageView from server, you can use below frameworks.

SDWebImage

You get completionBlock, progressBlock & many more properties that you can use to update your UI. It will notify you in blocks, then you can update whatever you want on UI.

Sample:

It's as simple as this code to just load image if the imageURL is valid (It's your case)

UIImageView *imageView;
[imageView setImageWithURL:[NSURL URLWithString:YOUR_URL]];

And it's also have rich methods like below

UIImageView *imageView;
[imageView setImageWithURL:[NSURL URLWithString:YOUR_URL] 
           placeholderImage:[UIImage imageNamed:@"placeholder.png"]
           completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType) 
           {
               // in "image" you'll get the downloaded image from the URL
               ... completion code here ...

           }];

setbackground loading with do while loop

2 Answers