keyboard notification observers (ios)

keyboard.m

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillShow:)
                                                 name:UIKeyboardWillChangeFrameNotification object:nil];
    
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(keyboardWillHide:)
                                                 name:UIKeyboardWillHideNotification object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillHideNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
}


- (void)keyboardWillShow:(NSNotification*)notification
{
    NSDictionary* info = [notification userInfo];
    CGSize kbSize = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    CGFloat duration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    UIViewAnimationCurve curve = [notification.userInfo[UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];
    UIViewAnimationOptions options = (curve << 16) | UIViewAnimationOptionBeginFromCurrentState;
    
    [self.view layoutIfNeeded];
    self.editorViewBottomConstraint.constant  = kbSize.height;
    [UIView animateWithDuration:duration
                          delay:0.0
                        options:options
                     animations:^{
                         [self.view layoutIfNeeded];
                     }
                     completion:^(BOOL success){
                         [self.messagesTableViewController goToBottom];
                     }];
        
}

- (void)keyboardWillHide:(NSNotification*)notification
{
    NSDictionary* info = [notification userInfo];
    CGFloat duration = [[info objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    [self.view layoutIfNeeded];
    self.editorViewBottomConstraint.constant  = 0;
    [UIView animateWithDuration:duration
                     animations:^{
                         [self.view layoutIfNeeded];
     }];
}