IPhone : Uitextfield Scrolling based on indexpath of Uitableview

Iam trying to set scrolling for textfield based on indexpath in uitableview, for this I have written my code in following manner

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];

- (void)keyboardWillShow:(NSNotification *)sender
{
    CGSize kbSize = [[[sender userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue].size;
    NSTimeInterval duration = [[[sender userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    [UIView animateWithDuration:duration animations:^
     {
         UIEdgeInsets edgeInsets = UIEdgeInsetsMake(0, 0, kbSize.height, 0);
         [self.mytableview setContentInset:edgeInsets];
         [self.mytableview setScrollIndicatorInsets:edgeInsets];

     }];
}

- (void)keyboardWillHide:(NSNotification *)sender
{


    NSTimeInterval duration = [[[sender userInfo] objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    [UIView animateWithDuration:duration animations:^
     {
         UIEdgeInsets edgeInsets = UIEdgeInsetsZero;
         [self.mytableview setContentInset:edgeInsets];
         [self.mytableview setScrollIndicatorInsets:edgeInsets];

         self.mytableview.contentOffset = CGPointMake(0,0);

     }];
}

By adding all those coding my textfields scrolling are working fine in Iphone 5(Retina 4 Inch) Device, but its not working Iphone 4 Device(Retina 3.5 Inch).

Note:Iam not Using autolayout ,Based on storyBoards i was working on different devices.

Can Anyone please give some helpful informaton. Thanks in Advance