Activity indicator not animating when creating a dispatch group in iOS - ios

Question

I want to display an activity indicator while performing some network calls in a dispatch_group_asyc block. But activity indicator only shows when the block finishes. I'm creating a dispatch_group_t because I need to get the result of the network calls before performing some other tasks. This is a simplified version of my code:
- (BOOL)doNetCall
{
[activityIndicator startAnimating];
__block BOOL netResult = NO;
dispatch_queue_t queue = dispatch_queue_create(netQueue, NULL);
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group,queue,^{
netResult = [service queryService];
});
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
dispatch_release(group);
dispatch_release(queue);
[activityIndicator stopAnimating];
if (netResult) {
// Perform some tasks
}
else {
[self showAlertView];
}
return netResult;
}
What am I doing wrong? Thanks!
EDIT: I need the method to wait until the block finishes in order to return the result I get

Answer 1

You should use activity indicator in this way:
[activityIndicator startAnimating];
dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
// Do something...
dispatch_async(dispatch_get_main_queue(), ^{
[activityIndicator stopAnimating];
});
});
If you're using group, just rewrite your code a little bit.

Answer 2

There doesn't appear to be any need for a dispatch group with what you are doing. Try this:
- (void)buttonClicked {
[activityIndicator startAnimating];
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
BOOL netResult = [service queryService];
dispatch_async(dispatch_get_main_queue(), ^{
[activityIndicator stopAnimating];
if (netResult) {
// perform some tasks
} else {
// show alert
}
});
});
}
If you have your queue, replace the call to dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0) with your own queue.