UIAlertView with text fields not moving up

Question

I want to display a prompt to get a user's username and password.

I am doing this by displaying a UIAlertView and adding UITextFields as subviews to it.

Recently I moved my project over to XCode 4.2 and I updated all my project settings. My base SDK is set to iOS 5.0 and my deployment target is set to 4.0.

I then noticed that it was only being built for armv7 architectures and so I changed that to include armv6 as well since I would like to support the iPhone 3G as well.

After doing this I noticed that the UIAlertView wasn't moving up as before and now it was being covered by the keyboard when it was displayed. I read in the Apple documentation that you shouldn't subclass UIAlertViews (http://developer.apple.com/library/ios/#documentation/uikit/reference/UIAlertView_Class/UIAlertView/UIAlertView.html) and so I changed the way I was doing things. This didn't solve the problem.

I have noticed that I can get it to work on my phone (an iPhone 4, so armv7 architecture) by setting the Build Setting - "Build active architecture only" to YES.

I suspect that the problem is something to do with trying to build for armv6 (and indeed removing this from the architectures I am trying to build for gives me alerts which move up correctly).

I suppose I should get to my question now... I'm struggling to understand why this is behaving the way it is. I read somewhere (can't find the link now) that you don't need to move the alert up manually when adding a text field to a UIAlertView in iOS 4 and above. Since I am building for at least iOS 4 shouldn't this work on both architectures?

Also, how can I get it to build for armv6 and still have alerts which move up correctly?

Edit: Maybe I was wrong but I have noticed that I have 2 instances of my phone which I can deploy the app to. Selecting the first one and building gives me an app where the UIAlertViews don't move up when they should, but selecting the second one makes it work properly. Would post a screenshot, but I'm a new user and so I don't have the permissions necessary yet...

Answer 1

Oki,

I've managed to come up with a solution which works and gets the UIAlertView to be in the correct position, but I'm still not entirely sure what the root cause of the problem is.

I solved it by responding to the UIAlertViewDelegate method willPresentAlertView: and doing the following

- (void) willPresentAlertView: (UIAlertView *) alertView {

    UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];

    if (keyWindow.center.y - alertView.center.y < 0.001f) {

        CGPoint center = [alertView center];
        center.y = center.y - 108.0f;
        [alertView setCenter:center];  
    }
}

It checks whether the UIAlertView is in the center of the screen and moves it up if it is (i.e. if the OS hasn't already calculated the correct position of it). Note: You would need to add a check for which specific orientation the device is in and then adjust the amount the alert is moved up accordingly if you wanted this to work for both portrait and landscape orientations.