iPhone Developer's Cookbook: ModalAlert Frozen - iphone

Question

I've used a recipe from the iPhone Developer's Cookbook called ModalAlert in order to get some text from a user; however, when the alert is shown, the keyboard and buttons are frozen. Here is the code for the modal alert.
+(NSString *) textQueryWith: (NSString *)question prompt: (NSString *)prompt button1: (NSString *)button1 button2:(NSString *) button2
{
// Create alert
CFRunLoopRef currentLoop = CFRunLoopGetCurrent();
ModalAlertDelegate *madelegate = [[ModalAlertDelegate alloc] initWithRunLoop:currentLoop];
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:question message:#"\n" delegate:madelegate cancelButtonTitle:button1 otherButtonTitles:button2, nil];
// Build text field
UITextField *tf = [[UITextField alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 260.0f, 30.0f)];
tf.borderStyle = UITextBorderStyleRoundedRect;
tf.tag = TEXT_FIELD_TAG;
tf.placeholder = prompt;
tf.clearButtonMode = UITextFieldViewModeWhileEditing;
tf.keyboardType = UIKeyboardTypeAlphabet;
tf.keyboardAppearance = UIKeyboardAppearanceAlert;
tf.autocapitalizationType = UITextAutocapitalizationTypeWords;
tf.autocorrectionType = UITextAutocorrectionTypeNo;
tf.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
// Show alert and wait for it to finish displaying
[alertView show];
while (CGRectEqualToRect(alertView.bounds, CGRectZero));
// Find the center for the text field and add it
CGRect bounds = alertView.bounds;
tf.center = CGPointMake(bounds.size.width / 2.0f, bounds.size.height / 2.0f - 10.0f);
[alertView addSubview:tf];
[tf release];
// Set the field to first responder and move it into place
[madelegate performSelector:#selector(moveAlert:) withObject:alertView afterDelay: 0.7f];
// Start the run loop
CFRunLoopRun();
// Retrieve the user choices
NSUInteger index = madelegate.index;
NSString *answer = [[madelegate.text copy] autorelease];
if (index == 0) answer = nil; // assumes cancel in position 0
[alertView release];
[madelegate release];
return answer;
}
Thanks!

Answer 1

You should probably check whether a UITextField's userInteractionEnabled property defaults to YES or NO.

Answer 2

// Put the modal alert inside a new thread. This happened to me before, and this is how i fixed it.
- (void)SomeMethod {
[NSThread detachNewThreadSelector:#selector(CheckCurrentPuzzle) toTarget:self withObject:nil]; }
-(void) CheckCurrentPuzzle {
NSAutoreleasePool *pool2 = [[NSAutoreleasePool alloc] init];
// code that should be run in the new thread goes here
if ([gameBoard AreAllCellsFilled]) {
if ([gameBoard FilledWithoutWin]) {
//only show this message once per puzzle
if (![currentPuzzle showedRemovalMessage]) {
NSArray *buttons = [NSArray arrayWithObject:#"Yes"];
if ([ModalAlert ask:#"blah blah blah" withTitle:#"Incomplete Puzzle" withCancel:#"No" withButtons:buttons] == 1) {
NSLog(#"Remove The Incorrect Cells");
[gameBoard RemoveIncorrect];
} else {
[gameSounds.bloop2 play];
}
}
} else {
if ([gameBoard IsBoardComplete]) {
[self performSelectorOnMainThread:#selector(WINNER) withObject:nil waitUntilDone:false];
}
}
}
[pool2 release];
}
-(void) WINNER {
//ladies and gentleman we have a winner
}

Answer 3

I had a problem similar to this in my educational game QPlus. It bugged me because I had the "exact" same code in two related apps, and they did not have the bug. It turned out that the bug was because the selector method was not declared in the header file. I am working in Xcode 4.2.
Details below:
In .m:
tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(emailLabelPressed)];
tapRecognizer.numberOfTapsRequired = 1;
[aLabel addGestureRecognizer:tapRecognizer];
[aLabel setUserInteractionEnabled:YES];
And later in the .m:
(void)emailLabelPressed {
//details
}
That works just fine in the simulator, but on an actual device the email interface presented modally will not edit. You can send or save as draft but no editing.
Then add this to the .h file:
(void)emailLabelPressed;
And voila, it works on the device. Of course this was the difference with the related apps - they both had the method declared in the header file. I would classify this as an iOS bug, but being such a novice developer I wouldn't presume to know.
Based on this, you may want to verify that your selector method moveAlert: is declared in your header file.
Enjoy,
Damien