UIView above UITableView not showing -- iOS - ios

Question

We're having a problem displaying a view above a tableView on iOS. Our approach
is to create a UIView that is a subview of a sublass of UIViewController, send
it to the back, and then bring it to the front upon didSelectRowAtIndexPath.
We're using an XIB to create the user interface. The view hierarchy is like
this:
View
-- UIView ("loading..." view)
-- -- UILabel ("loading...")
-- -- UIActivityIndicatorView
-- UITableView
-- UILabel
Here is what we're doing to try to display the "loading" view:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
// Create a request to the server based on the user's selection in the table view
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:url];
NSError *err;
// Show the "loading..." message in front of all the other views.
[self.view bringViewToFront:self.loadingView];
[self.loadingWheel startAnimating];
// Make the request
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&err];
// Stop animating the activity indicator.
[loadingWheel stopAnimating];
// other stuff...
}
Whenever we leave the "loading" view at the front of all the other views in the
XIB, we can see that it looks as we want. However, when we leave the loading
view at the back (per the view hierarchy above) and then try to bring it to the
front, the view never displays. Printing out self.view.subviews shows that our
loading view is in fact in the view hierarchy. Interestingly, if we try to
change something else in our view within didSelectRowAtIndexPath (for example,
changing the background color of a label that's already displaying in the view),
the change never shows on the simulator.

Answer 1

The problem is the synchronous request. It blocks the main thread, and so the activity indicator does not get a chance to show.
A simple solution would be to asynchronously load the data on a global queue, and when everything is loaded, call back to the main queue.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// Make the request
NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:&err];
dispatch_async(dispatch_get_main_queue(), ^{
// Stop animating the activity indicator.
[loadingWheel stopAnimating];
// other stuff...
});
});
While the solution above works, it blocks a global queue and so it is not ideal. Have a look at the asynchronous loading via NSURLConnection. It is explained in great detail in Apple's "URL Loading System Programming Guide".