Uiactivityindicator not showing in subview - ios

Question

I am trying to show a spinner in a subview on a tableview controller on my main thread. The view is only showing on occasions and generally appears to be showing after my background thread has finished. Here is my code:
[self.view addSubview:spinnerView];
[self.view bringSubviewToFront:spinnerView];
self.spinnerView.layer.cornerRadius = 8;
self.spinnerView.center = CGPointMake(160, 150);
[spinner startAnimating];
dispatch_queue_t downloadQueue = dispatch_queue_create("downloader", NULL);
dispatch_async(downloadQueue, ^ {
dispatch_async(dispatch_get_main_queue(), ^{
[NSThread sleepForTimeInterval:10];
// Add recurring transactions if necessary
if (tran.recur.id != 0) {
[Utilities addRecurringTransactionsUpToCurrentMonthByTransaction:tran];
}
[spinner stopAnimating];
[self dismissViewControllerAnimated:YES completion:nil];
});
});
dispatch_release(downloadQueue);
}
}

Answer 1

Since all UI is running on main thread, you must call performSelectorOnMainThread:withObject:waitUntilDone: like below:
[self.view addSubview:spinnerView];
[self.view bringSubviewToFront:spinnerView];
self.spinnerView.layer.cornerRadius = 8;
self.spinnerView.center = CGPointMake(160, 150);
[spinner performSelectorOnMainThread:#selector(startAnimating) withObject:nil waitUntilDone:NO];
dispatch_queue_t downloadQueue = dispatch_queue_create("downloader", NULL);
dispatch_async(downloadQueue, ^ {
dispatch_async(dispatch_get_main_queue(), ^{
[NSThread sleepForTimeInterval:10];
// Add recurring transactions if necessary
if (tran.recur.id != 0) {
[Utilities addRecurringTransactionsUpToCurrentMonthByTransaction:tran];
}
[spinner performSelectorOnMainThread:#selector(stopAnimating) withObject:nil waitUntilDone:NO];
[self dismissViewControllerAnimated:YES completion:nil];
});
});
dispatch_release(downloadQueue);