Why does the whole view jerk up when the keyboard hides? - ios

Question

When the keyboardWillHideFunction is called the whole view from the viewController jerks upward. Below is a video of the probelm occuring.
vidoe of screen jerking
Below is the code I am using to control keyboard notifications. I have tried playing around with the animation times and the layout constraints but I havent been able to get much further. Any suggestions on how to fix it thank you.
EDITED CODE BASED ON SUGGESTIONS- Ive tried creating a variable for the layout constraints as suggested however the problem still persists any ideas why?
import UIKit
import Foundation
extension UIView {
func currentFirstResponder() -> UIResponder? {
if self.isFirstResponder {
return self
}
for view in self.subviews {
if let responder = view.currentFirstResponder() {
return responder
}
}
return nil
}
}
extension Notification.Name{
static let showKeyboard = Notification.Name("showKeyboard")
}
class KeyboardSlider: NSObject {
// variables to hold and process information from the view using this class
weak var view: UIView?
var searchBarTopTags:SearchBarTopTagsViewController?
var amountToShiftBy:CGFloat!
var originalFrame:CGRect!
var previewController:PreviewController!
#objc func keyboardWillShow(notification: NSNotification) {
self.searchBarTopTags?.myViewBottomLayoutConstraint.constant = -self.getKeyboardHeight(notification as! Notification) + previewController.view.safeAreaInsets.bottom
UIView.animate(withDuration: 0, animations: {
self.view?.layoutIfNeeded()
self.searchBarTopTags?.myView.layoutIfNeeded()
})
}
#objc func keyboardWillHide(notification:NSNotification){
self.searchBarTopTags?.myViewBottomLayoutConstraint.constant = 0
UIView.animate(withDuration: 0, animations: {
self.view?.layoutIfNeeded()
self.searchBarTopTags?.myView.layoutIfNeeded()
})
}
func getKeyboardHeight(_ notification:Notification) -> CGFloat {
// get exact height of keyboard on all devices and convert to float value to return for use
let userInfo = notification.userInfo
let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
return keyboardSize.cgRectValue.height
}
func subscribeToKeyboardNotifications(view: UIView) {
// assigning view to class' counterpart
self.view = view
// when UIKeyboardWillShow do keyboardWillShow function
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil)
}
func subscribeToKeyboardNotifications(view: UIView, previewController:PreviewController? = nil) {
// assigning view to class' counterpart
self.view = view
self.searchBarTopTags = previewController?.searchBarTopTags
self.previewController = previewController
// when UIKeyboardWillShow do keyboardWillShow function
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: .UIKeyboardWillHide, object: nil)
}
func unsubscribeFromKeyboardNotifications() {
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide, object: nil)
}
}
ORIGINAL CODE:
import UIKit
import Foundation
extension UIView {
func currentFirstResponder() -> UIResponder? {
if self.isFirstResponder {
return self
}
for view in self.subviews {
if let responder = view.currentFirstResponder() {
return responder
}
}
return nil
}
}
extension Notification.Name{
static let showKeyboard = Notification.Name("showKeyboard")
}
class KeyboardSlider: NSObject {
// variables to hold and process information from the view using this class
weak var view: UIView?
var searchBarTopTags:SearchBarTopTagsViewController?
var amountToShiftBy:CGFloat!
var originalFrame:CGRect!
#objc func keyboardWillShow(notification: NSNotification) {
self.originalFrame = self.searchBarTopTags?.myView.frame
self.amountToShiftBy = (self.searchBarTopTags?.view.frame.maxY)! - self.getKeyboardHeight(notification as! Notification) - (self.searchBarTopTags?.myView.frame.height)!
self.amountToShiftBy = (searchBarTopTags?.view.bounds.height)! - self.getKeyboardHeight(notification as! Notification) - (searchBarTopTags?.myView.bounds.height)!
self.searchBarTopTags?.myView.bottomAnchor.constraint(equalTo: (self.searchBarTopTags?.view.bottomAnchor)!, constant: -self.amountToShiftBy).isActive = true
UIView.animate(withDuration: 0, animations: {
self.view?.layoutIfNeeded()
self.searchBarTopTags?.view.layoutIfNeeded()
self.searchBarTopTags?.myView.layoutIfNeeded() })
}
#objc func keyboardWillHide(notification:NSNotification){
self.searchBarTopTags?.myView.bottomAnchor.constraint(equalTo: (self.searchBarTopTags?.view.bottomAnchor)!, constant: 0).isActive = true
UIView.animate(withDuration: 0, animations: {
self.view?.layoutIfNeeded()
self.searchBarTopTags?.view.layoutIfNeeded()
self.searchBarTopTags?.myView.layoutIfNeeded()
})
}
func getKeyboardHeight(_ notification:Notification) -> CGFloat {
// get exact height of keyboard on all devices and convert to float value to return for use
let userInfo = notification.userInfo
let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
return keyboardSize.cgRectValue.height
}
func subscribeToKeyboardNotifications(view: UIView) {
// assigning view to class' counterpart
self.view = view
// when UIKeyboardWillShow do keyboardWillShow function
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil)
}
func subscribeToKeyboardNotifications(view: UIView, seachBarTopTagsVC:SearchBarTopTagsViewController? = nil) {
// assigning view to class' counterpart
self.view = view
self.searchBarTopTags = seachBarTopTagsVC
// when UIKeyboardWillShow do keyboardWillShow function
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(notification:)), name: .UIKeyboardWillHide, object: nil)
}
func unsubscribeFromKeyboardNotifications() {
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide, object: nil)
}
}

Answer 1

Inside keyboardWillShow there is
self.searchBarTopTags?.myView.bottomAnchor.constraint(equalTo: (self.searchBarTopTags?.view.bottomAnchor)!, constant: -self.amountToShiftBy).isActive = true
And inside keyboardWillHide
self.searchBarTopTags?.myView.bottomAnchor.constraint(equalTo: (self.searchBarTopTags?.view.bottomAnchor)!, constant: 0).isActive = true
which off course will cause a conflict as the keyboard hides/shows , you need to create the bottom constraint only once say in viewDidLoad , then play with the constant value inside those methods , like this
var bottomConstraint:NSLayoutConstraint!
//
bottomConstraint = self.searchBarTopTags?.myView.bottomAnchor.constraint(equalTo: (self.searchBarTopTags?.view.bottomAnchor)!, constant: 0)
bottomConstraint.isActive = true
//
#objc func keyboardWillShow(notification: NSNotification) {
// other code
bottomConstraint.constant = -self.amountToShiftBy
}
#objc func keyboardWillHide(notification: NSNotification) {
bottomConstraint.constant = 0
// other code
}

Answer 2

Each time you call the following line, a new constraint will be added:
self.searchBarTopTags?.myView.bottomAnchor.constraint(equalTo: (self.searchBarTopTags?.view.bottomAnchor)!, constant: -self.amountToShiftBy).isActive = true
You need to add a reference to the constraint and just change its constant.
let constraint = self.searchBarTopTags?.myView.bottomAnchor.constraint...
contraint.constant = ...