How to detect if a key is pressed in iOS? [duplicate] - ios

Question

I am trying to check when a text field changes, equivalent too the function used for textView - textViewDidChange so far I have done this:
func textFieldDidBeginEditing(textField: UITextField) {
if self.status.text == "" && self.username.text == "" {
self.topRightButton.enabled = false
} else {
self.topRightButton.enabled = true
}
}
Which kind of works, but the topRightButton is enabled as soon as the text field is pressed on, I want it to be enabled only when text is actually typed in?

Answer 1

SWIFT
Swift 4.2
textfield.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)
and
#objc func textFieldDidChange(_ textField: UITextField) {
}
SWIFT 3 & swift 4.1
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), for: .editingChanged)
and
func textFieldDidChange(_ textField: UITextField) {
}
SWIFT 2.2
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)
and
func textFieldDidChange(textField: UITextField) {
//your code
}
OBJECTIVE-C
[textField addTarget:self action:#selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];
and textFieldDidChange method is
-(void)textFieldDidChange :(UITextField *) textField{
//your code
}

Answer 2

You can make this connection in interface builder.
In your storyboard, click the assistant editor at the top of the screen (two circles in the middle).
Ctrl + Click on the textfield in interface builder.
Drag from EditingChanged to inside your view controller class in the assistant view.
Name your function ("textDidChange" for example) and click connect.

Answer 3

Swift 5.0
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
for: .editingChanged)
and handle method:
#objc func textFieldDidChange(_ textField: UITextField) {
}
Swift 4.0
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
for: UIControlEvents.editingChanged)
and handle method:
#objc func textFieldDidChange(_ textField: UITextField) {
}
Swift 3.0
textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)
and handle method:
func textFieldDidChange(textField: UITextField) {
}

Answer 4

The way I've handled it so far: in UITextFieldDelegate
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
// text hasn't changed yet, you have to compute the text AFTER the edit yourself
let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)
// do whatever you need with this updated string (your code)
// always return true so that changes propagate
return true
}
Swift4 version
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
return true
}

Answer 5

Swift 3
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(sender:)), for: UIControlEvents.editingChanged)

Answer 6

textField(_:shouldChangeCharactersIn:replacementString:) worked for me in Xcode 8, Swift 3 if you want to check every single keypress.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
// Whatever code you want to run here.
// Keep in mind that the textfield hasn't yet been updated,
// so use 'string' instead of 'textField.text' if you want to
// access the string the textfield will have after a user presses a key
var statusText = self.status.text
var usernameText = self.username.text
switch textField{
case self.status:
statusText = string
case self.username:
usernameText = string
default:
break
}
if statusText == "" && usernameText == "" {
self.topRightButton.enabled = false
} else {
self.topRightButton.enabled = true
}
//Return false if you don't want the textfield to be updated
return true
}

Answer 7

Swift 3.0.1+ (Some of the other swift 3.0 answers are not up to date)
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
for: UIControlEvents.editingChanged)
func textFieldDidChange(_ textField: UITextField) {
}

Answer 8

You can use this delegate method from UITextFieldDelegate. It fires with every character change.
(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)
However THIS ONLY FIRES BEFORE a change is made (indeed, a change is only made if you do return true from here).

Answer 9

Swift 4
Conform to UITextFieldDelegate.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
// figure out what the new string will be after the pending edit
let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
// Do whatever you want here
// Return true so that the change happens
return true
}

Answer 10

Maybe use RxSwift ?
need
pod 'RxSwift', '~> 3.0'
pod 'RxCocoa', '~> 3.0'
add imports obviously
import RxSwift
import RxCocoa
So u have a textfield : UITextField
let observable: Observable<String?> = textField.rx.text.asObservable()
observable.subscribe(
onNext: {(string: String?) in
print(string!)
})
U have other 3 methods..
onError
onCompleted
onDisposed
onNext

Answer 11

Swift 4
textField.addTarget(self, action: #selector(textIsChanging), for: UIControlEvents.editingChanged)
#objc func textIsChanging(_ textField:UITextField) {
print ("TextField is changing")
}
If you want to make a change once the user has typed in completely (It will be called once user dismiss keyboard or press enter).
textField.addTarget(self, action: #selector(textDidChange), for: UIControlEvents.editingDidEnd)
#objc func textDidChange(_ textField:UITextField) {
print ("TextField did changed")
}

Answer 12

You should follow this steps:
Make a Outlet reference to the textfield
AssignUITextFieldDelegate to the controller class
Configure yourTextField.delegate
Implement whatever function you need
Sample code:
import UIKit
class ViewController: UIViewController, UITextFieldDelegate {
#IBOutlet var yourTextFiled : UITextField!
override func viewDidLoad() {
super.viewDidLoad()
yourTextFiled.delegate = self
}
func textFieldDidEndEditing(_ textField: UITextField) {
// your code
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
// your code
}
.
.
.
}

Answer 13

In case it is not possible to bind the addTarget to your UITextField, I advise you to bind one of them as suggested above, and insert the code for execution at the end of the shouldChangeCharactersIn method.
nameTextField.addTarget(self, action: #selector(RegistrationViewController.textFieldDidChange(_:)), for: .editingChanged)
#objc func textFieldDidChange(_ textField: UITextField) {
if phoneNumberTextField.text!.count == 17 && nameTextField.text!.count > 0 {
continueButtonOutlet.backgroundColor = UIColor(.green)
} else {
continueButtonOutlet.backgroundColor = .systemGray
}
}
And in call in shouldChangeCharactersIn func.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let text = textField.text else {
return true
}
let lastText = (text as NSString).replacingCharacters(in: range, with: string) as String
if phoneNumberTextField == textField {
textField.text = lastText.format("+7(NNN)-NNN-NN-NN", oldString: text)
textFieldDidChange(phoneNumberTextField)
return false
}
return true
}

Answer 14

There's now a UITextField delegate method available on iOS13+
optional func textFieldDidChangeSelection(_ textField: UITextField)

Answer 15

txf_Subject.addTarget(self, action:#selector(didChangeFirstText), for: .editingChanged)
#objc func didChangeText(textField:UITextField) {
let str = textField.text
if(str?.contains(" "))!{
let newstr = str?.replacingOccurrences(of: " ", with: "")
textField.text = newstr
}
}
#objc func didChangeFirstText(textField:UITextField) {
if(textField.text == " "){
textField.text = ""
}
}

Answer 16

Swift 4.2
write this in viewDidLoad
// to detect if TextField changed
TextField.addTarget(self, action: #selector(textFieldDidChange(_:)),
for: UIControl.Event.editingChanged)
write this outside viewDidLoad
#objc func textFieldDidChange(_ textField: UITextField) {
// do something
}
You could change the event by UIControl.Event.editingDidBegin or what ever you want to detect.

Answer 17

This is how you can add a textField text change listener using Swift 3:
Declare your class as UITextFieldDelegate
override func viewDidLoad() {
super.viewDidLoad()
textField.delegate = self
textField.addTarget(self, action: #selector(UITextFieldDelegate.textFieldShouldEndEditing(_:)), for: UIControlEvents.editingChanged)
}
Then just traditionally add a textFieldShouldEndEditing function:
func textFieldShouldEndEditing(_ textField: UITextField) -> Bool { // do stuff
return true
}

Answer 18

Just in case you are interested in a SwiftUI solution, this it's working for me:
TextField("write your answer here...",
text: Binding(
get: {
return self.query
},
set: { (newValue) in
self.fetch(query: newValue) // any action you need
return self.query = newValue
}
)
)
I have to say it's not my idea, I read it in this blog: SwiftUI binding: A very simple trick

Answer 19

You can manage editing either by "shouldchangecharacter" delgate or "begin and end" textfield delegate. Don't forget to set delegate
I am manage to do this using "did begin and end editing" below.
//MARK:- TextViewDelegate
extension ViewController: UITextFieldDelegate {
func textFieldDidEndEditing(_ textField: UITextField) {
let count = self.tfEmail.text?.count ?? 0
if textField == self.tfEmail {
if count == 0{
//Empty textfield
}else{
//Non-Empty textfield
}
}
}
func textFieldDidBeginEditing(_ textField: UITextField) {
if textField == self.tfEmail{
//when user taps on textfield
}
}
}

Answer 20

swift 4
In viewDidLoad():
//ADD BUTTON TO DISMISS KEYBOARD
// Init a keyboard toolbar
let toolbar = UIView(frame: CGRect(x: 0, y: view.frame.size.height+44, width: view.frame.size.width, height: 44))
toolbar.backgroundColor = UIColor.clear
// Add done button
let doneButt = UIButton(frame: CGRect(x: toolbar.frame.size.width - 60, y: 0, width: 44, height: 44))
doneButt.setTitle("Done", for: .normal)
doneButt.setTitleColor(MAIN_COLOR, for: .normal)
doneButt.titleLabel?.font = UIFont(name: "Titillium-Semibold", size: 13)
doneButt.addTarget(self, action: #selector(dismissKeyboard), for: .touchUpInside)
toolbar.addSubview(doneButt)
USDTextField.inputAccessoryView = toolbar
Add this function:
#objc func dismissKeyboard() {
//Causes the view (or one of its embedded text fields) to resign the first responder status.
view.endEditing(true)
}