activity indicator appearing only for a second - ios

Question

I have 2 views
1) A
2) B
When I segue from view A to view B, it takes a long while to load, so I added an activity indicator in the segue.
My problem is, when I segue over to view B, my screen freezes(loads) in view A and only for a split second, it shows the activity indicator before going onto view B.
How do I make sure the activity indicator appears before it starts to load.
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
[self useActivityIndicator];
if ([[segue identifier] isEqualToString:#"ShowAdsDetail"])
{
//do anything that needs to be done
}
}
-(void)useActivityIndicator{
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
[activityView startAnimating];
subView.hidden = NO;
}

Answer 1

I had a similar issue with a UIActivityIndicator that was animating too fast. The segue was pushing the next view controller right away and barely showing the activity indicator.
In case this can help others - I was able to fix it by implementing performSelector:withObject:afterDelay and then, in the removeSpinner method, calling my performSegueWithIdentifier method.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
[tableView deselectRowAtIndexPath:[tableView indexPathForSelectedRow] animated:YES];
[self.spinner startAnimating];
[self performSelector:#selector(removeSpinner:) withObject:self.spinner afterDelay:2.0];
}
- (void)removeSpinner: (UIActivityIndicatorView *)spinner {
[self.spinner stopAnimating];
[self.spinner removeFromSuperview];
[self performSegueWithIdentifier:#"showMyPlans" sender:nil];
}

Answer 2

Just change your code like:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[self useActivityIndicator];
});
if ([[segue identifier] isEqualToString:#"ShowAdsDetail"])
{
//do anything that needs to be done
}
}
-(void)useActivityIndicator
{
dispatch_async(dispatch_get_main_queue(),^{
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
[activityView startAnimating];
subView.hidden = NO;
});
}