Can't see my alertView unless I comment out automatic dismission

Question

I am implementing a simple alert view with activity indicator to show to the user while the app is performing the restore of the database. Everything is fine except that I can't see the alert view, unless I comment out the automatic dismiss line (last one here).

Ok, the restore of the database is quite quick, but still I would expect to see it even if for an instant, no? I can see the screen get's a little darker during animation but that's all. I also tried putting a for loop to extend the time, the time extends but still no alert view.

There is nothing wrong in the way the alert view is called, since if I comment the dismiss, I can see it...only forever. Anyone has an idea here?

Before anyone says it, I tried changing the delegate of the alertView to self as posted here, but it didn't help.

// First we prepare the activity indicator view to show progress indicator
UIActivityIndicatorView * activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];

[activityView setFrame:CGRectMake(121.0f, 50.0f, 37.0f, 37.0f)];
[activityView startAnimating];

// Then we put it in an alert view
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Loading" message:nil delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];
[alertView addSubview:activityView];
[alertView show];

// Finally we operate the restore
[[SQLManager sharedSQL] restoreDatabase:[restoreDatabaseURL path]];

// And we can dismiss the alert view with the progress indicator
[alertView dismissWithClickedButtonIndex:0 animated:NO];

Answer 1

Im not sure why this happens, but I encounter it occasionally as well. One way I have gotten something like this to work is by using performSelector:withObject:afterDelay: on the next call, like this:

// First we prepare the activity indicator view to show progress indicator
UIActivityIndicatorView * activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];

[activityView setFrame:CGRectMake(121.0f, 50.0f, 37.0f, 37.0f)];
[activityView startAnimating];

// Then we put it in an alert view
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Loading" message:nil delegate:nil cancelButtonTitle:nil otherButtonTitles:nil];
[alertView addSubview:activityView];
[alertView show];

// Finally we operate the restore
// [[SQLManager sharedSQL] restoreDatabase:[restoreDatabaseURL path]];
[[SQLManager sharedSQL] performSelector:@selector(restoreDatabase:) withObject:[restoreDatabaseURL path] afterDelay:0.25];


// And we can dismiss the alert view with the progress indicator
[alertView dismissWithClickedButtonIndex:0 animated:NO];

performSelector Documentation

Answer 2

Sounds like it's dismissing itself almost instantaneously. If you add a for loop, it will likely freeze all other computations which means your activity view won't show up until the loop breaks.

You could try using a NSTimer to call another function to determine if the restore is complete or not;

// Setup our the timer
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                                  target:self 
                                                selector:@selector(checkRestore)
                                                userInfo:nil
                                                 repeats:YES];


// Timer function checking for completion
-(void)checkRestore {
    if (restore is complete) {
        [alertView dismissWithClickedButtonIndex:0 animated:NO];
    }
}