CODEWITHSUNDEEP
ioscocoa-touch
JoJo
JoJo

Reputation: 20115

How to prevent multiple UIAlertView from stacking up?

I'm using MPMoviePlayerController in iOS. I'm listening on any errors it may have while playing videos. In my error handlers, I pop up an UIAlertView. Sometimes errors may occur in quick succession of each other and thus multiple alert boxes will stack up. For a better user experience, I wish to not pop up another alert if an earlier one is still displayed.

Upvotes: 8

Views: 10032

Answers (6)

Manab Kumar Mal
Manab Kumar Mal

Reputation: 21398

It should work:

-(BOOL) doesAlertViewExist 
{
    if ([[UIApplication sharedApplication].keyWindow isMemberOfClass:[UIWindow class]])
    {
        return NO;//AlertView does not exist on current window
    }
    return YES;//AlertView exist on current window
}

Upvotes: 0

malhal
malhal

Reputation: 30811

Use the new UIAlertViewController. If you try to present an alert while another is in view it ignores it and outputs the warning shown below. It's a nasty side affect for people who want the traditional behaviour of stacked alerts but for your case it's a good solution.

Warning: Attempt to present <UIAlertController: 0x7f9ef34c17e0>  on <MasterViewController: 0x7f9ef344ec90> which is already presenting (null)

Upvotes: 0

Kanhaiya Sharma
Kanhaiya Sharma

Reputation: 1038

When an alert appears, it will be moved to a _UIAlertOverlayWindow. Therefore, a pretty fragile method is to iterate through all windows and check if there's any UIAlertView subviews.

-(BOOL)checkAlertViewVisibleStatus
{
  for (UIWindow* window in [UIApplication sharedApplication].windows) 
   {
     NSArray* subviews = window.subviews;
      if ([subviews count] > 0)
        if ([[subviews objectAtIndex:0] isKindOfClass:[UIAlertView class]])
          return YES;
    }
return NO;
}

This is undocumented as it depends on internal view hierarchy, although Apple cannot complain about this. A more reliable but even more undocumented method is to check if `

[_UIAlertManager visibleAlert]

` is nil.

These methods can't check if a UIAlertView from SpringBoard is shown.

Upvotes: 1

Ben.Vineyard
Ben.Vineyard

Reputation: 1169

As far as I know, the only way is to keep track of whether or not an alert is currently being displayed and/or one is currently being dismissed within your application. Try showing the alert in the appDelegate, and then using a notification to notify the appDelegate each time the alert is closed. This way the appDelegate keeps track of whether or not there is an alert with a boolean flag variable.

Upvotes: 0

Lily Ballard
Lily Ballard

Reputation: 185871

You can implement this yourself trivially. Since you're displaying the alert, and you're also the alert's delegate so you know when it's gone, you can easily track whether there's an alert visible just by setting a boolean flag upon alert show and alert hide. That way if the boolean is set, you can quash any subsequent alerts.

Upvotes: 1

mopsled
mopsled

Reputation: 8515

Try this:

Set a boolean to true when you pop up an alert, set it to false when you close an alert, and always check the boolean to see if it's true before you pop up an event. If it is true, you'll know you have an alert window already showing.

You can find this solution and some other discussion here.

Upvotes: 6

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