Detect Backspace in Empty Uitextfield

Detect backspace in empty UITextField

This may be a long shot but it could work. Try setting the text field's text to a zero width space character \u200B. When backspace is pressed on a text field that appears empty, it will actually delete your space. Then you can just reinsert the space.

May not work if the user manages to move the caret to the left of the space.

Detect backspace Event in UITextField

Swift 4.2

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    if let char = string.cString(using: String.Encoding.utf8) {
        let isBackSpace = strcmp(char, "\\b")
        if (isBackSpace == -92) {
            print("Backspace was pressed")
        }
    }
    return true
}

Older Swift version

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let  char = string.cStringUsingEncoding(NSUTF8StringEncoding)!
    let isBackSpace = strcmp(char, "\\b")

    if (isBackSpace == -92) {
        println("Backspace was pressed")
    }
    return true
}

Detect backspace in empty UITextField Swift Working Sample

If you use Jacob's solution, the deleteBackward method will be called with the current UITextField instance. So you can add a protocol to that UITextField class and pass it back to your view.
Something like this:

protocol MyTextFieldDelegate: class {
   func backwardDetected(textField: MyTextField)
}

class MyTextField: UITextField {
   weak var myTextFieldDelegate: MyTextFieldDelegate?

   override func deleteBackward() {
     super.deleteBackward()

     self.myTextFieldDelegate?.backwardDetected(textField: self)
   }
}

Detect backspace in empty UITextField

This may be a long shot but it could work. Try setting the text field's text to a zero width space character \u200B. When backspace is pressed on a text field that appears empty, it will actually delete your space. Then you can just reinsert the space.

May not work if the user manages to move the caret to the left of the space.

iOS: Detect backspace in empty UITextField with UITextField subclass

The problem is with your outlet. The property is defined with your custom class but in a Interface Builder you added a plain old UITextField. Hence the error at runtime. In Interface Buldier, update the text field's class to be your custom class.

textfield backspace action identify when textfield is empty?

followed by @Marmik Shah and @Prashant Tukadiya answer here I add my answer , for quick answer I taken the some code from here

step 1 :

create the IBOutletCollection for your all textfields as well as don't forget to set the tag in all textfields in the sequence order, for e.g [1,2,3,4,5,6]

class ViewController: UIViewController{

@IBOutlet var OTPTxtFields: [MyTextField]! // as well as set the tag for textfield in the sequence order

 override func viewDidLoad() {
    super.viewDidLoad()

    //change button color and other options
    OTPTxtFields.forEach { $0.textColor  = .red;  $0.backspaceTextFieldDelegate = self }
    OTPTxtFields.first.becomeFirstResponder()
}

step 2 :

in your current page UITextField delegate method

extension ViewController : UITextFieldDelegate, MyTextFieldDelegate {

func textFieldDidEnterBackspace(_ textField: MyTextField) {
    guard let index = OTPTxtFields.index(of: textField) else {
        return
    }

    if index > 0 {
        OTPTxtFields[index - 1].becomeFirstResponder()
    } else {
        view.endEditing(true)
    }
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let newString = ((textField.text)! as NSString).replacingCharacters(in: range, with: string)


    if newString.count < 2 && !newString.isEmpty {
        textFieldShouldReturnSingle(textField, newString : newString)
      //  return false
    }

     return newString.count < 2 || string == ""
    //return true
}
override public func canPerformAction(_ action: Selector, withSender sender: Any?) -> Bool {
    if action == #selector(copy(_:)) || action == #selector(paste(_:)) {
        return false
    }

    return true
}
func textFieldShouldReturnSingle(_ textField: UITextField, newString : String)
{
    let nextTag: Int = textField.tag + 1
    textField.text = newString
    let nextResponder: UIResponder? = textField.superview?.viewWithTag(nextTag)
    if let nextR = nextResponder
    {
        // Found next responder, so set it.

        nextR.becomeFirstResponder()
    }
    else
    {
        // Not found, so remove keyboard.
        textField.resignFirstResponder()
        callOTPValidate()
    }
}

}

Step 3:

create the textfield class for access the backward function

class MyTextField: UITextField {
weak var myTextFieldDelegate: MyTextFieldDelegate?

override func deleteBackward() {
    if text?.isEmpty ?? false {
        myTextFieldDelegate?.textFieldDidEnterBackspace(self)
    }

    super.deleteBackward()
}

}

protocol MyTextFieldDelegate: class {
func textFieldDidEnterBackspace(_ textField: MyTextField)
}

step - 4

finally follow the @Marmik Shah answer for custom class for your UITextField

Step 5

get the values from each textfield use this

func callOTPValidate(){
    var texts:  [String] = []
    OTPTxtFields.forEach {  texts.append($0.text!)}
    sentOTPOption(currentText: texts.reduce("", +))

}

  func  sentOTPOption(currentText: String)   {
    print("AllTextfieldValue == \(currentText)")
  }

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