calling web services with asynchImageView

Question

I am having a problem in calling web services when the image are being loaded in the tableView with AsynchImageView files .

Below are the steps of my problem:

1. I call the web service and when it returns the data i reload the UITableView and load all images with AsynchImageView . The web service returns url of images and some text data .
2. While the images are being loaded , if I call the same web service again then it runs for 30 seconds and then it times out without returning anything but after that time it works fine whenever I call it .

Here is my code for calling services:

-(void)getUserNotificationsPage:(int)page CallBack:(getNotifications)callback{
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_async(queue, ^ {
       @try {

            getNotificationsArrayResponseCallback=callback;


            NSURLRequest * urlRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@?token=%@&page=%@",GET_USER_NOTIFICATIONS,[[NSUserDefaults standardUserDefaults]objectForKey:@"token"],[NSString stringWithFormat:@"%i",page]]]];


            NSError *err;
            NSData *returnData = [NSURLConnection sendSynchronousRequest:urlRequest returningResponse:nil error:&err];
            if(err){
                returnData=[NSMutableData data];
            }

            NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];


   dispatch_async(dispatch_get_main_queue(), ^ {

 id json = [NSJSONSerialization JSONObjectWithData:returnData options:NSJSONReadingMutableContainers error:nil];

        NSArray *returnArray=[json objectForKey:@"notifications"];

                getNotificationsArrayResponseCallback(returnArray,YES);

            });

        }
        @catch (NSException *exception) {


            dispatch_async(dispatch_get_main_queue(), ^ {

                UIAlertView *alert=[[UIAlertView alloc]initWithTitle:LANGUAGE(@"Unknown error occurred") message:nil delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
                [alert show];


                getNotificationsArrayResponseCallback(nil,NO);

            });
        }        
     });
}

3. If I remove the code where the images are being loaded with asynchImageview then I call call the web service at any time and the response is fast at any time .

   AsynchImageView *userProfileImageView =[[AsynchImageView alloc] initWithFrameURLStringAndTag:CGRectMake(5, 215, 70, 70) :[NSString stringWithFormat:@"%@%@",SERVER_URL,"some url" ];
   
   [userProfileImageView setBackgroundColor:[UIColor clearColor]];
   
   [userProfileImageView loadImageFromNetwork];
   
   [cell addSubview:userProfileImageView];
   

As you can see if I comment the line

[userProfileImageView loadImageFromNetwork];

then I can call the web service any number of times and the response is quick but when the asynchimage view is loading the images and then i call the service then it will time out for that time only . For further calling service works fine .

I think this is the issue with threading or calling serveral url requests at the same time .

Answer 1

is this the class you are using? AsynchImageView

If so, it doesn't actually look like his NSURLConnection is being handled in the background. It looks like it's on the main thread.

I have used this other library in the past with success AsyncImageView

If you look in this other library, they are using a proper dispatch queue for running the background. The other class doesn't have that.

dispatch_async(dispatch_get_main_queue(), ^(void) {

Answer 2

Make custom cell and inside of that cell, put this method

-(void)setImageWithUrl:(NSString *)imageUrl
{
    NSURL *urlImage = [NSURL URLWithString:imageUrl];
    [self.loadingIndicator startAnimating];

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
    dispatch_async(queue, ^{

        NSError* error = nil;
        NSData *imageData = [NSData dataWithContentsOfURL:urlImage options:nil error:&error];

        if(error){
            dispatch_sync(dispatch_get_main_queue(), ^{

                [self.imgVw setImage:[UIImage imageNamed:@"placeholder.png"]];
                [self.loadingIndicator stopAnimating];
                [[NSURLCache sharedURLCache] removeAllCachedResponses];
            });
        }else{
            UIImage *image = [UIImage imageWithData:imageData];
            dispatch_sync(dispatch_get_main_queue(), ^{

                [self.imgVw setImage:image]; 
                [self.loadingIndicator stopAnimating];
                [[NSURLCache sharedURLCache] removeAllCachedResponses];
            });
        }
    });
}

Now, call this in cellForRowAtIndexPath method. Put it inside cell nil condition, so that it does not called everytime you scroll. Make comment in case of any doubt.

if(custCellObj == nil)
{
      NSString *imgUrl = [yourArray objectAtIndex:indexPath.row];
      [custCellObj setImageWithUrl:imgUrl];
}