When I've tried How to you set the maximum number of characters that can be entered into a UITextField using swift?, I saw that if I use all 10 characters, I can't erase the character too.
The only thing I can do is to cancel the operation (delete all the characters together).
Does anyone know how to not block the keyboard (so that I can't add other letters/symbols/numbers, but I can use the backspace)?
This question is related to
ios
swift
uitextfield
character
max
The answer is
Beware of the undo bug for UITextField mentioned in this post: Set the maximum character length of a UITextField
here is how you fix it in swift
if(range.length + range.location > count(textField.text)) {
return false;
}
I have been using this protocol / extension in one of my apps, and it's a little more readable. I like how it recognizes backspaces and explicitly tells you when a character is a backspace.
Some things to consider:
1.Whatever implements this protocol extension needs to specify a character limit. That's typically going to be your ViewController, but you could implement character limit as a computed property and return something else, for example a character limit on one of your models.
2. You will need to call this method inside of your text field's shouldChangeCharactersInRange delegate method. Otherwise you won't be able to block text entry by returning false, etc.
3. You will probably want to allow backspace characters through. That's why I added the extra function to detect backspaces. Your shouldChangeCharacters method can check for this and return 'true' early on so you always allow backspaces.
protocol TextEntryCharacterLimited{
var characterLimit:Int { get }
}
extension TextEntryCharacterLimited{
func charactersInTextField(textField:UITextField, willNotExceedCharacterLimitWithReplacementString string:String, range:NSRange) -> Bool{
let startingLength = textField.text?.characters.count ?? 0
let lengthToAdd = string.characters.count
let lengthToReplace = range.length
let newLength = startingLength + lengthToAdd - lengthToReplace
return newLength <= characterLimit
}
func stringIsBackspaceWith(string:String, inRange range:NSRange) -> Bool{
if range.length == 1 && string.characters.count == 0 { return true }
return false
}
}
If any of you are interested, I have a Github repo where I've taken some of this character limit behavior and put into an iOS framework. There's a protocol you can implement to get a Twitter-like character limit display that shows you how far you've gone above the character limit.
Swift 3
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let nsString = NSString(string: textField.text!)
let newText = nsString.replacingCharacters(in: range, with: string)
return newText.characters.count <= limitCount
}
I do it like this:
func checkMaxLength(textField: UITextField!, maxLength: Int) {
if (countElements(textField.text!) > maxLength) {
textField.deleteBackward()
}
}
The code works for me. But I work with storyboard. In Storyboard I add an action for the text field in the view controller on editing changed.
If you want to overwrite the last letter:
let maxLength = 10
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if range.location > maxLength - 1 {
textField.text?.removeLast()
}
return true
}
func checkMaxLength(textField: UITextField!, maxLength: Int) {
if (textField.text!.characters.count > maxLength) {
textField.deleteBackward()
}
}
a small change for IOS 9
Im using this;
Limit 3 char
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if let txt = textField.text {
let currentText = txt + string
if currentText.count > 3 {
return false
}
return true
}
return true
}
Here is my version of code. Hope it helps!
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let invalidCharacters = NSCharacterSet(charactersInString: "0123456789").invertedSet
if let range = string.rangeOfCharacterFromSet(invalidCharacters, options: nil, range:Range<String.Index>(start: string.startIndex, end: string.endIndex))
{
return false
}
if (count(textField.text) > 10 && range.length == 0)
{
self.view.makeToast(message: "Amount entry is limited to ten digits", duration: 0.5, position: HRToastPositionCenter)
return false
}
else
{
}
return true
}
You can use in swift 5 or swift 4 like image look like bellow
- Add textField in View Controller
- Connect to text to ViewController
add the code in view ViewController
class ViewController: UIViewController , UITextFieldDelegate { @IBOutlet weak var txtName: UITextField! var maxLen:Int = 8; override func viewDidLoad() { super.viewDidLoad() txtName.delegate = self } func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { if(textField == txtName){ let currentText = textField.text! + string return currentText.count <= maxLen } return true; } }
You can download Full Source form GitHub: https://github.com/enamul95/TextFieldMaxLen
Update for Swift 4
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let text = textField.text else { return true }
let newLength = text.count + string.count - range.length
return newLength <= 10
}
In Swift 4
10 Characters limit for text field and allow to delete(backspace)
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if textField == userNameFTF{
let char = string.cString(using: String.Encoding.utf8)
let isBackSpace = strcmp(char, "\\b")
if isBackSpace == -92 {
return true
}
return textField.text!.count <= 9
}
return true
}
Swift 5
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let MAX_LENGTH = 4
let updatedString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
return updatedString.count <= MAX_LENGTH
}
Since delegates are a 1-to-1 relationship and I might want to use it elsewhere for other reasons, I like to restrict textfield length adding this code within their setup:
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)!
setup()
}
required override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
func setup() {
// your setup...
setMaxLength()
}
let maxLength = 10
private func setMaxLength() {
addTarget(self, action: #selector(textfieldChanged(_:)), for: UIControlEvents.editingChanged)
}
@objc private func textfieldChanged(_ textField: UITextField) {
guard let text = text else { return }
let trimmed = text.characters.prefix(maxLength)
self.text = String(trimmed)
}
You need to check whether the existing string plus the input is greater than 10.
func textField(textField: UITextField!,shouldChangeCharactersInRange range: NSRange, replacementString string: String!) -> Bool {
NSUInteger newLength = textField.text.length + string.length - range.length;
return !(newLength > 10)
}
Add More detail from @Martin answer
// linked your button here
@IBAction func mobileTFChanged(sender: AnyObject) {
checkMaxLength(sender as! UITextField, maxLength: 10)
}
// linked your button here
@IBAction func citizenTFChanged(sender: AnyObject) {
checkMaxLength(sender as! UITextField, maxLength: 13)
}
func checkMaxLength(textField: UITextField!, maxLength: Int) {
// swift 1.0
//if (count(textField.text!) > maxLength) {
// textField.deleteBackward()
//}
// swift 2.0
if (textField.text!.characters.count > maxLength) {
textField.deleteBackward()
}
}
you can extend UITextField and add an @IBInspectable object for handle it:
SWIFT 5
import UIKit
private var __maxLengths = [UITextField: Int]()
extension UITextField {
@IBInspectable var maxLength: Int {
get {
guard let l = __maxLengths[self] else {
return 150 // (global default-limit. or just, Int.max)
}
return l
}
set {
__maxLengths[self] = newValue
addTarget(self, action: #selector(fix), for: .editingChanged)
}
}
@objc func fix(textField: UITextField) {
if let t = textField.text {
textField.text = String(t.prefix(maxLength))
}
}
}
and after that define it on attribute inspector
I posted a solution using IBInspectable, so you can change the max length value both in interface builder or programmatically. Check it out here
Source: Stackoverflow.com