What is the reason the UIKeyBoardWIllShowNotification called once ?

Question

Hello all,

I am using keyboard will show and hide notification for sliding the view to get the visible text view.

I have a tab bar application with six tabs.

In each view I am using the navigation controller.

In the detail view of each table view cell I am using the keyboard notifications.

So the problem is that the keyboard notifications work for the first time that I will use . on on the other tabs it won't work .

The code is as follows :

[[NSNotificationCenter defaultCenter] addObserver:self
               selector:@selector(keyboardWasShown:)
                name:UIKeyboardDidShowNotification
                 object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
               selector:@selector(keyboardWasHidden:)
                name:UIKeyboardDidHideNotification
                 object:nil];

and the methods

- (void)keyboardWasShown:(NSNotification *)aNotification {
    if ( keyboardShown )
        return;


        NSDictionary *info = [aNotification userInfo];
        NSValue *aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey];
        CGSize keyboardSize = [aValue CGRectValue].size;

        NSTimeInterval animationDuration = 0.300000011920929;
        CGRect frame = self.view.frame;
        frame.origin.y -= keyboardSize.height-100;
        frame.size.height += keyboardSize.height-100;
        [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
        [UIView setAnimationDuration:animationDuration];
        self.view.frame = frame;
        [UIView commitAnimations];

    viewMoved = YES;

    keyboardShown = YES;
}
- (void)keyboardWasHidden:(NSNotification *)aNotification {
    if ( viewMoved  && tvAddreview) {
        NSDictionary *info = [aNotification userInfo];
        NSValue *aValue = [info objectForKey:UIKeyboardBoundsUserInfoKey];
        CGSize keyboardSize = [aValue CGRectValue].size;

        NSTimeInterval animationDuration = 0.300000011920929;
        CGRect frame = self.view.frame;
        frame.origin.y += keyboardSize.height-100;
        frame.size.height -= keyboardSize.height-100;
        [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
        [UIView setAnimationDuration:animationDuration];
        self.view.frame = frame;
        [UIView commitAnimations];

        viewMoved = NO;
    }

    keyboardShown = NO;
}

Answer 1

you should dothis in eachClass like this:

-(void) viewWillAppear: (BOOL)animated
{
    [super viewWillAppear:animated];

    NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
    [nc addObserver:self selector:@selector(keyboardWasShown:) name: UIKeyboardWillShowNotification object:nil];
    [nc addObserver:self selector:@selector(keyboardWasHidden:) name: UIKeyboardWillHideNotification object:nil];

}



- (void) viewWillDisappear: (BOOL)animated{

    [super viewWillDisappear:animated];

    NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
    [nc removeObserver:self name: UIKeyboardWillShowNotification object:nil];
    [nc removeObserver:self name: UIKeyboardWillHideNotification object:nil];
}

because the notifications are on the application level not to your class level. So if you have added them in one class and not in all classes, then going to the next class. the notification will still call the the key keyboardWasShown: and the other from the class in which you added the notifications hence your local variables like... viewMoved = YES;

keyboardShown = YES;

will throw the bad excess exceptions

In your case it is also required to do in all 6 view controllers

Hope this helps.