UITextField: When beginning input, textfield bounces up, and then bounces down - ios

Question

I've seen this with UITextView too. Clearly, I'm missing something pretty basic.
I've tried:
- Setting textsize to small
- UITextField: Setting 1 line, no resize
- Removing the ability to move the texfield
import UIKit
class XViewController: UIViewController, UITextFieldDelegate, UIGestureRecognizerDelegate {
// UI elements
let cancelButton = UIButton()
let okButton = UIButton()
var image:UIImage?
var previewImageView:UIImageView = UIImageView()
let textField = UITextField()
let tapGestureRecognizer = UITapGestureRecognizer()
let textFieldTypingPositionY:CGFloat = 200
var textFieldActualPositionY:CGFloat!
let textFieldHeight:CGFloat = 40
var draggingTextField:Bool = false
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
setupTextField()
}
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString text: String) -> Bool {
let textFieldSize = textField.text!.characters.count
let textSize = text.characters.count
if text == "\n" && textFieldSize == 0 {
// press return on empty textfield
textField.text = ""
hideTextField()
return true
} else if textFieldSize == 1 && text == "" {
// backspace to empty
textField.text = ""
hideTextField()
return true
} else if text == "\n" {
textField.resignFirstResponder()
} else if (textFieldSize + textSize) > 30 {
let diff = (textFieldSize - textSize) - 30
textField.text = (text as NSString).substringToIndex(diff - 1)
}
return true
}
func setupTextField() {
// TextView
textField.translatesAutoresizingMaskIntoConstraints = false
textField.backgroundColor = UIColor.blackColor().colorWithAlphaComponent(0.7)
textField.textColor = UIColor.whiteColor()
textField.font = UIFont.systemFontOfSize(14.0)
textField.textAlignment = NSTextAlignment.Center
textField.text = ""
textField.hidden = true
textField.delegate = self
self.view.addSubview(textField);
// Text view constraints
let leftConstraint = textField.leftAnchor.constraintEqualToAnchor(view.leftAnchor)
let rightConstraint = textField.rightAnchor.constraintEqualToAnchor(view.rightAnchor)
let heightConstraint = textField.heightAnchor.constraintEqualToConstant(textFieldHeight)
let verticalConstraint = textField.topAnchor.constraintEqualToAnchor(view.topAnchor, constant: 200)
NSLayoutConstraint.activateConstraints([leftConstraint, rightConstraint, heightConstraint, verticalConstraint])
// Tap gesture recognizer; if no text view is visible, shows text view at vertical location of tap
tapGestureRecognizer.delegate = self
tapGestureRecognizer.addTarget(self, action: "tapGesture:")
view.addGestureRecognizer(tapGestureRecognizer)
}
func tapGesture(rec:UITapGestureRecognizer) {
// Show the textView in a location?
if textField.hidden == false {
if (textField.text!.characters.count == 0) {
hideTextField()
} else {
restoreTextFieldPosition()
}
} else {
moveTextFieldToEditingPosition()
}
}
func moveTextFieldToEditingPosition() {
// Textview animates into position a la snapchat
self.textField.userInteractionEnabled = false
textField.hidden = false
UIView.animateWithDuration(0.2, animations: { () -> Void in
self.textField.center.y = self.textFieldTypingPositionY
}, completion: { (Bool) -> Void in
self.textField.userInteractionEnabled = true
self.textField.becomeFirstResponder()
})
}
func hideTextField() {
// Hide text view and reset position
textField.resignFirstResponder()
textField.userInteractionEnabled = false
UIView.animateWithDuration(0.2, animations: { () -> Void in
}, completion: { (Bool) -> Void in
self.textField.hidden = true
})
}
func restoreTextFieldPosition() {
// Restore original position of textview after exiting keyboard
self.textField.userInteractionEnabled = false
textField.resignFirstResponder()
UIView.animateWithDuration(0.2, animations: { () -> Void in
}, completion: { (Bool) -> Void in
self.textField.userInteractionEnabled = true
})
}
}

Answer 1

I had this issue with iOS 9. It was ok on iOS 7 and 8. Basically I have a UITextField in a collection view cell. Sometimes when the user is done typing and editing ends, the text "bounces" up then down again into its correct position. Very strange and annoying glitch. Simply making this tweak fixed the issue on iOS 9 and proved to be safe on iOS 7 and 8:
- (void)textFieldDidEndEditing:(UITextField *)textField
{
[textField layoutIfNeeded]; //Fixes iOS 9 text bounce glitch
//...other stuff
}

Answer 2

this is strange behaviour of textField. I have same issue and the reason is what you are changing the position of textField.
Solution
whatever you have write code for changing position (Y position in your case) using uiview.animation.... Remove this code
And i'm damn sure this bounce will occur when you remove the focus or switch to another control.
Finally, Remove animation code or leave this bounce animation (not bad).
:)

Answer 3

Not sure if you solved this, but for me it was because I had a piece of code in my UITextFieldDelegate calling layoutIfNeeded - which was causing all the auto-layout constraints to be recalculated.
I removed the layoutIfNeeded and seemed to have fixed the bouncing