How to test if keyboard is covering UITextField in UITableView? - ios

Question

How can I check if the keyboard is covering a first responder inside a UIScrollView which may or may not be a UITableView? Note the UIScrollView will not necessarily cover the entire viewController's view and may be contained in a modal view (UIModalPresentationFormSheet).
I'm using this modified code from Apple's reference documentation and example, but CGRectContainsPoint will return false even when the keyboard is clearly covering the first responder. It's obvious I'm not using convertRect:toView correctly.
Also, Apple's code does not take into account that the view is not full-screen, so setting the scrollView's contentInset to the full height of the keyboard isn't a great solution -- it should only be inset for the portion of the keyboard covering the firstResponder.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
// self.scrollView can be a tableView or not. need to handle both
UIView *firstResponderView = [self.scrollView findFirstResponder];
if (!firstResponderView)
return;
NSDictionary* info = [aNotification userInfo];
CGRect rect = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
// convertRect:toView? convertRect:fromView? Always confusing
CGRect kbRect = [self.scrollView convertRect:rect toView:nil];
CGRect viewRect = [self.scrollView convertRect:firstResponderView.bounds toView:nil];
// doesn't work. convertRect misuse is certainly to blame
if (!CGRectContainsPoint(kbRect, firstResponderView.frame.origin))
return;
// Only inset to the portion which the keyboard covers?
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbRect.size.height, 0.0);
self.scrollView.contentInset = contentInsets;
self.scrollView.scrollIndicatorInsets = contentInsets;
}

Answer 1

Without further testing or having a deep look at the logic, this line seems odd:
CGRect kbRect = [self.scrollView convertRect:rect toView:nil];
The keyboard rect (that is included in the notification) is in window coordinates and you probably want to convert it into the scroll view coordinate system. [viewA convertRect:rect toView:viewB] converts rect from viewA's coordinate system to viewB's coordinate system, so you are actually doing the opposite of what you should be doing (as you suspected).
What I'm usually doing is this:
- (void)keyboardWillShow:(NSNotification *)aNotification
{
NSDictionary *info = [aNotification userInfo];
CGRect kbRect = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
kbRect = [self.view.window convertRect:kbRect toView:self.view]; // convert to local coordinate system, otherwise it is in window coordinates and does not consider interface orientation
_keyboardSize = kbRect.size; // store for later use
[UIView animateWithDuration:0.25 animations:^{
UIEdgeInsets insets = UIEdgeInsetsMake(0.0f, 0.0f, MAX(0.0f, CGRectGetMaxY(_tableView.frame) - CGRectGetMinY(kbRect)), 0.0f); // NB: _tableView is a direct subview of self.view, thus _tableView.frame and kbRect are in the same coordinate system
_tableView.contentInset = insets;
_tableView.scrollIndicatorInsets = insets;
[self scrollToActiveTextField]; // here I adapt the content offset to ensure that the active text field is fully visible
}];
}