How properly addObserver in UITextField subclass for getting when Keyboard is visible?

Question

I have subclass of UITextField. I want to know when keyboard is visible. This will help me to move all view up if the keyboard is hiding my text field.

In my subclass I add observer as follows:

- (id)initWithCoder:(NSCoder *)aDecoder{
    if (self = [super initWithCoder:aDecoder]) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardIsVisible:) name:UIKeyboardDidShowNotification object:nil];
    }
    return self;
}

I expect to catch the size of the keyboard:

/* Get height when keyboard is visible */
- (void)keyboardIsVisible:(NSNotification*)notification
{
    NSDictionary* keyboardInfo = [notification userInfo];
    NSValue* keyboardFrameBegin = [keyboardInfo valueForKey:UIKeyboardFrameBeginUserInfoKey];
    CGRect keyboardFrameBeginRect = [keyboardFrameBegin CGRectValue];

    _keyboardHeight =keyboardFrameBeginRect.size.height;

}

I will use ivar _keyboardHeight to decide if I have to move keyboard:

/* Move keyboard */
-(void)showKeyboardWithMove {

    CGRect screenRect = [[UIScreen mainScreen] bounds];
    ////CGFloat screenWidth = screenRect.size.width;
    CGFloat screenHeight = screenRect.size.height;


    if (self.frame.origin.y + self.frame.size.height > screenHeight - _keyboardHeight) {
        double offset = screenHeight - _keyboardHeight - self.frame.origin.y - self.frame.size.height;
        CGRect rect = CGRectMake(0, offset, self.superview.frame.size.width, self.superview.frame.size.height);

        [UIView beginAnimations:nil context:NULL];
        [UIView setAnimationDuration:0.3];

        self.superview.frame = rect;

        [UIView commitAnimations];
    }

}

From my view controller class I call showKeyboardWithMove:

- (void)textFieldDidBeginEditing:(MyCustomTextField *)textField
{
    // Call method for moving control when Keyboard is shown and hides it
    [textField showKeyboardWithMove];
}

- (void)textFieldDidEndEditing:(MyCustomTextField *)textField
{
    // Call method for returning control when Keyboard is hidden
    [textField hideKeyboardWithMove];
}

The problem is that keyboardIsVisible is not fire when I first show keyboard. So I think that my observer is not properly coded. Any ideas?

Possible duplicate of [How to make a UITextField move up when keyboard is present](http://stackoverflow.com/questions/1126726/how-to-make-a-uitextfield-move-up-when-keyboard-is-present) — PAC, Feb 16 '16 at 07:20

score 0 · Answer 1 · answered Oct 02 '14 at 08:44

0

Try to remove your

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

to viewWillAppear. In my case it works. Also I use

UIKeyboardWillShowNotification

instead of

UIKeyboardDidShowNotification

answered Oct 02 '14 at 08:44

Victorianec

587
1
6
15

it does not working. When I move `addObserver` to `viewWillAppear`, observer is not set at all. – new2ios Oct 02 '14 at 09:00

score 0 · Answer 2 · edited May 23 '17 at 10:28

In objective-c

To move your view up, when keyboard was visible can be done by multiple ways, see this link

In Swift:

Add the following two definition in viewDidLoad() function first:

NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)

NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil)

and then add the following two methods in your class.

func keyboardWillShow(notification: NSNotification) {    
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
        self.view.frame.size.height -= keyboardSize.height
    }

}

func keyboardWillHide(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
        self.view.frame.size.height += keyboardSize.height
    }
}

How properly addObserver in UITextField subclass for getting when Keyboard is visible?

2 Answers2