On selecting a textfield, adjust view height for keyboard - ios

Question

I have a ViewController (login view) in xib which has 2 UITextField and 1 UIButton component. The view hierarchy is
UIView
-> UIScrollView
-> UIView (contentView)
-> UITextField
-> UITextField
-> UIButton
I am using autolayout for the view. The UIScrollView has 4 constraints i.e., leading, trailing, top & bottom aligned to its superview (UIViewController view). ContentView has 4 constraints i.e., leading, trailing, top & bottom to its superview (UIScrollView) and width matching UIViewController view.
I have followed the steps as in Apple documentation to scroll up or down when user selects UITextField so that keyboard is not on top of UITextField.
When keyboard is shown scrollview is scrolled up but when keyboard is hidden scrollview does not scroll back. Any help is appreciated.
override func viewDidLoad() {
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
func keyboardWillHide(notification: NSNotification) {
let contentInsets: UIEdgeInsets = UIEdgeInsets.zero
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
}
func keyboardWillShow(notification: NSNotification) {
if let activeField = self.activeField, let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
let contentInsets = UIEdgeInsets(top: 0.0, left: 0.0, bottom: keyboardSize.height, right: 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
var aRect = self.view.frame
aRect.size.height -= keyboardSize.size.height
if (!aRect.contains(activeField.frame.origin)) {
self.scrollView.scrollRectToVisible(activeField.frame, animated: true)
}
}
}

Answer 1

This problem with the keyboard is explained in detail in the apple documentation:
https://developer.apple.com/library/content/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html
Alternatively, try the following code:
func registerForKeyboardNotifications(){
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWasShown(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillBeHidden(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
func deregisterFromKeyboardNotifications(){
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: nil)
NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: nil)
}
func keyboardWasShown(notification: NSNotification){
self.scrollView.isScrollEnabled = true
var info = notification.userInfo!
let keyboardSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue.size
let contentInsets : UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, keyboardSize!.height, 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
var aRect : CGRect = self.view.frame
aRect.size.height -= keyboardSize!.height
if let activeField = self.activeField {
if (!aRect.contains(activeField.frame.origin)){
self.scrollView.scrollRectToVisible(activeField.frame, animated: true)
}
}
}
func keyboardWillBeHidden(notification: NSNotification){
var info = notification.userInfo!
let keyboardSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue.size
let contentInsets : UIEdgeInsets = UIEdgeInsetsMake(0.0, 0.0, -keyboardSize!.height, 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
self.view.endEditing(true)
self.scrollView.isScrollEnabled = false
}
func textFieldDidBeginEditing(_ textField: UITextField){
activeField = textField
}
func textFieldDidEndEditing(_ textField: UITextField){
activeField = nil
}

Answer 2

The scrollView contentInset.top was not 0.0 hence i was facing the problem. After changing contentInset.top properly scrollView set to original position after keyboard was hidden.
func keyboardWillShow(notification: NSNotification) {
self.scrollView.isScrollEnabled = true
var info = notification.userInfo!
let keyboardSize = (info[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue.size
let contentInsets : UIEdgeInsets = UIEdgeInsetsMake(self.scrollView.contentInset.top, 0.0, keyboardSize!.height, 0.0)
self.scrollView.contentInset = contentInsets
self.scrollView.scrollIndicatorInsets = contentInsets
var aRect : CGRect = self.view.frame
aRect.size.height -= keyboardSize!.height
if let activeField = self.activeField {
if (!aRect.contains(activeField.frame.origin)){
self.scrollView.scrollRectToVisible(activeField.frame, animated: true)
}
}
}