Text Field Drops Below Keyboard Upon Entering Text in Text Field - ios

Question

I have a strange issue with regard to entering text into a text field. I am currently using the code below. My code is modeled after the answer here.
class RocketViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UITextFieldDelegate, NSFetchedResultsControllerDelegate {
var offsetY:CGFloat = 0
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(RocketViewController.keyboardFrameChangeNotification(notification:)), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
}
#objc func keyboardFrameChangeNotification(notification: Notification) {
if let userInfo = notification.userInfo {
let keyBoardFrame = userInfo[UIKeyboardFrameEndUserInfoKey] as? CGRect
let animationDuration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? Double ?? 0
let animationCurveRawValue = (userInfo[UIKeyboardAnimationCurveUserInfoKey] as? Int) ?? Int(UIViewAnimationOptions.curveEaseInOut.rawValue)
let animationCurve = UIViewAnimationOptions(rawValue: UInt(animationCurveRawValue))
if let _ = keyBoardFrame, keyBoardFrame!.intersects(self.mainStackView.frame) {
self.offsetY = self.mainStackView.frame.maxY - keyBoardFrame!.minY
UIView.animate(withDuration: animationDuration, delay: TimeInterval(0), options: animationCurve, animations: {
self.mainStackView.frame.origin.y = self.mainStackView.frame.origin.y - self.offsetY
self.rocketSelectTable.frame.origin.y = self.rocketSelectTable.frame.origin.y - self.offsetY
}, completion: nil)
} else {
if self.offsetY != 0 {
UIView.animate(withDuration: animationDuration, delay: TimeInterval(0), options: animationCurve, animations: {
self.mainStackView.frame.origin.y = self.mainStackView.frame.origin.y + self.offsetY
self.rocketSelectTable.frame.origin.y = self.rocketSelectTable.frame.origin.y + self.offsetY
self.offsetY = 0
}, completion: nil)
}
}
}
}
}
In my view I have a table view with a fetched results controller as its data source, and below that are the text fields in a stack view, called mainStackView, that are eventually saved in a core data store.
I have gone through several iterations of this code with the same result, whether I compute the offset off the first responder, or simply the stack view. When a text field becomes the first responder, the view slides up nicely with the keyboard. However, as soon as I attempt to type in the field, the view snaps back to its original position. I am sure I am making a newbie mistake, but I can't figure out what I am doing wrong, and I have found nothing in my searches, except a similar question for android. Thanks in advance.

Answer 1

While I have not determined why I was seeing the behavior with the text field that I was seeing with changing the frame, I was able to stop the behavior by using a CGAffineTransform instead. My code is now:
#objc func keyboardFrameChangeNotification(notification: Notification) {
if let userInfo = notification.userInfo {
let keyBoardFrame = userInfo[UIKeyboardFrameEndUserInfoKey] as? CGRect
let animationDuration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? Double ?? 0
let animationCurveRawValue = (userInfo[UIKeyboardAnimationCurveUserInfoKey] as? Int) ?? Int(UIViewAnimationOptions.curveEaseInOut.rawValue)
let animationCurve = UIViewAnimationOptions(rawValue: UInt(animationCurveRawValue))
if let _ = keyBoardFrame, keyBoardFrame!.intersects(self.mainStackView.frame) {
self.offsetY = self.mainStackView.frame.maxY - keyBoardFrame!.minY
let transformUp = CGAffineTransform.init(translationX: 0, y: (0 - self.offsetY))
UIView.animate(withDuration: animationDuration, delay: TimeInterval(0), options: animationCurve, animations: {
self.mainStackView.transform = transformUp
self.rocketSelectTable.transform = transformUp
}, completion: nil)
} else {
if self.offsetY != 0 {
UIView.animate(withDuration: animationDuration, delay: TimeInterval(0), options: animationCurve, animations: {
self.mainStackView.transform = CGAffineTransform.identity
self.rocketSelectTable.transform = CGAffineTransform.identity
self.offsetY = 0
}, completion: nil)
}
}
}
This code smoothly animates the movement of the views, and there is no snap back to the original position while typing in the text field. I hope this helps someone else.