Question

I have a UIScrollView designed to enable scrolling when the keyboard is up. The positioning of the scroll view is fine in portrait mode; I have positioned it in Interface Builder, and set the contentSize in my code …

CGSize scrollContentSize = CGSizeMake(360, 221);
self.scrollView.contentSize = scrollContentSize;

However, I am struggling to work out how to change the position of the scrollview so it works effectively when the orientation changes to landscape (and back). Do I somehow need to position it in Interface Builder for landscape(?), and then change the content size in my code dependent on the orientation?

Edit:
Im getting the keyboard size as follows, and changing the content size. This works when i move to Portrait, but the frame is positioned slightly wrong in landscape mode.

 (void)keyboardWillShow:(NSNotification *)n{

    if (keyboardIsShown) {
    return;
    }

    NSDictionary* userInfo = [n userInfo];

    CGRect _keyboardEndFrame;
    [[userInfo valueForKey:UIKeyboardFrameEndUserInfoKey] getValue:&_keyboardEndFrame];
    CGFloat _keyboardHeight;
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    if (orientation == UIDeviceOrientationPortrait || orientation == UIDeviceOrientationPortraitUpsideDown) {
    _keyboardHeight = _keyboardEndFrame.size.height;
    }
    else {
        _keyboardHeight = _keyboardEndFrame.size.width;
    }

    // resize the noteView
    CGRect viewFrame = self.scrollView.frame;
     viewFrame.size.height -= _keyboardHeight;

    if (UIDeviceOrientationIsPortrait(orientation)){
        CGSize scrollContentSize = CGSizeMake(360, 221);
        self.scrollView.contentSize = scrollContentSize;
    }
    else if (UIDeviceOrientationIsLandscape(orientation)){
        CGSize scrollContentSize = CGSizeMake(520, 275);
        self.scrollView.contentSize = scrollContentSize;
    }

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDuration:0.3];
    [self.scrollView setFrame:viewFrame];
    [UIView commitAnimations];

    keyboardIsShown = YES;
}

Answer 1

What you want to do is figure out the where the top of the keyboard is relative to the view that contains your scrollView. Fortunately, there is a function in UIView called convertRect:fromView: that will take the frame from one coordinate system and map it to another coordinate system. In your case, you know the frame of the keyboard relative to the main window, but would like to know where the top of the keyboard is relative to the view that contains your scrollView. Once you know where the top of the keyboard intersects with your view, you can modify the height of your scrollView to accommodate.

Below is a snippet of code I use, which I found somewhere online and don’t take credit for. In your view controller you want to be notified of keyboard show and hide events:

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

Then implement keyboardWillShow: and keyboardWillHide: like this:

// When the keyboard shows resize self.textView to touch the top of the keyboard.
-(void)keyboardWillShow:(NSNotification *)_notification {
    NSDictionary  *userInfo = [_notification userInfo];

    NSTimeInterval animationDuration;
    UIViewAnimationCurve animationCurve;
    CGRect keyboardEndFrame;
    [[userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] getValue:&animationCurve];
    [[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] getValue:&animationDuration];
    [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] getValue:&keyboardEndFrame];

        // Here we figure out where the keyboard overlaps with self.view
        // self.view contains self.textView
    CGRect keyboardFrame = [self.view convertRect:keyboardEndFrame fromView:nil];
    CGFloat textViewWidth = self.view.frame.size.width;

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:animationDuration];
    [UIView setAnimationCurve:animationCurve];
    self.textView.frame = CGRectMake(0, 0, textViewWidth, keyboardFrame.origin.y);
    [UIView commitAnimations];
}

// When the keyboard hides return self.textView to fullscreen
-(void)keyboardWillHide:(NSNotification *)_notification {
    NSDictionary  *userInfo = [_notification userInfo];

    NSTimeInterval animationDuration;
    UIViewAnimationCurve animationCurve;
    CGRect keyboardEndFrame;
    [[userInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] getValue:&animationCurve];
    [[userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] getValue:&animationDuration];
    [[userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] getValue:&keyboardEndFrame];

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:animationDuration];
    [UIView setAnimationCurve:animationCurve];
    self.textView.frame = self.view.frame;
    [UIView commitAnimations];  
}

The snippet contains some extra stuff to animate the transition in sync with the keyboard animation.

In this snippet I use self.textView, which you will probably want to change to self.scrollView. What’s great about this code is that it works in all orientations and on the iPad. Take a look at the code and hopefully it’ll be self explanatory.