The recommended way from Apple is to change the contentInset
of the UIScrollView
. It is a very elegant solution, because you do not have to mess with the contentSize
.
Following code is copied from the Keyboard Programming Guide, where the handling of this issue is explained. You should have a look into it.
// Call this method somewhere in your view controller setup code.
- (void)registerForKeyboardNotifications
{
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWasShown:)
name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillBeHidden:)
name:UIKeyboardWillHideNotification object:nil];
}
// Called when the UIKeyboardDidShowNotification is sent.
- (void)keyboardWasShown:(NSNotification*)aNotification
{
NSDictionary* info = [aNotification userInfo];
CGSize kbSize = [[info objectForKey:UIKeyboardFrameBeginUserInfoKey] CGRectValue].size;
UIEdgeInsets contentInsets = UIEdgeInsetsMake(0.0, 0.0, kbSize.height, 0.0);
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
// If active text field is hidden by keyboard, scroll it so it's visible
// Your application might not need or want this behavior.
CGRect aRect = self.view.frame;
aRect.size.height -= kbSize.height;
if (!CGRectContainsPoint(aRect, activeField.frame.origin) ) {
CGPoint scrollPoint = CGPointMake(0.0, activeField.frame.origin.y-kbSize.height);
[scrollView setContentOffset:scrollPoint animated:YES];
}
}
// Called when the UIKeyboardWillHideNotification is sent
- (void)keyboardWillBeHidden:(NSNotification*)aNotification
{
UIEdgeInsets contentInsets = UIEdgeInsetsZero;
scrollView.contentInset = contentInsets;
scrollView.scrollIndicatorInsets = contentInsets;
}
Swift version:
func registerForKeyboardNotifications() {
NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardAppear(_:)), name: NSNotification.Name.UIKeyboardDidShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(onKeyboardDisappear(_:)), name: NSNotification.Name.UIKeyboardDidHide, object: nil)
}
// Don't forget to unregister when done
deinit {
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardDidShow, object: nil)
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardDidHide, object: nil)
}
@objc func onKeyboardAppear(_ notification: NSNotification) {
let info = notification.userInfo!
let rect: CGRect = info[UIKeyboardFrameBeginUserInfoKey] as! CGRect
let kbSize = rect.size
let insets = UIEdgeInsetsMake(0, 0, kbSize.height, 0)
scrollView.contentInset = insets
scrollView.scrollIndicatorInsets = insets
// If active text field is hidden by keyboard, scroll it so it's visible
// Your application might not need or want this behavior.
var aRect = self.view.frame;
aRect.size.height -= kbSize.height;
let activeField: UITextField? = [addressTextView, servicePathTextView, usernameTextView, passwordTextView].first { $0.isFirstResponder }
if let activeField = activeField {
if !aRect.contains(activeField.frame.origin) {
let scrollPoint = CGPoint(x: 0, y: activeField.frame.origin.y-kbSize.height)
scrollView.setContentOffset(scrollPoint, animated: true)
}
}
}
@objc func onKeyboardDisappear(_ notification: NSNotification) {
scrollView.contentInset = UIEdgeInsets.zero
scrollView.scrollIndicatorInsets = UIEdgeInsets.zero
}