Allowing single digit in UITextField in iOS

Question

I have a Verification ViewController, I get 4 digit verification code by SMS and I need to enter those code to login, I have created the ViewController

Answer 1

Swift 4

Inspired by @Anurag Soni and @Varun Naharia answers

Variant A

extension EnterConfirmationCodeTextField: UITextFieldDelegate {

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        guard let textFieldCount = textField.text?.count else { return false }

        // Сlosure
        let setValueAndMoveForward = {
            textField.text = string
            let nextTag = textField.tag + 1
            if let nextResponder = textField.superview?.viewWithTag(nextTag) {
                nextResponder.becomeFirstResponder()
            }
        }

        // Сlosure
        let clearValueAndMoveBack = {
            textField.text = ""
            let previousTag = textField.tag - 1
            if let previousResponder = textField.superview?.viewWithTag(previousTag) {
                previousResponder.becomeFirstResponder()
            }
        }

        if textFieldCount < 1 && string.count > 0 {

            setValueAndMoveForward()

            if textField.tag == 4 {
                print("Do something")
            }

            return false

        } else if textFieldCount >= 1 && string.count == 0 {

            clearValueAndMoveBack()
            return false

        } else if textFieldCount >= 1 && string.count > 0 {

            let nextTag = self.tag + 1
            if let previousResponder = self.superview?.viewWithTag(nextTag) {
                previousResponder.becomeFirstResponder()

                if let activeTextField = previousResponder as? UITextField {
                    activeTextField.text = string
                }
            }

            return false
        }

        return true

    }

}

Variant B (a little bit another behavior):

extension EnterConfirmationCodeTextField: UITextFieldDelegate {

        func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
            guard let textFieldCount = textField.text?.count else { return false }

            // Сlosure
            let setValueAndMoveForward = {
                textField.text = string
                let nextTag = textField.tag + 1
                if let nextResponder = textField.superview?.viewWithTag(nextTag) {
                    nextResponder.becomeFirstResponder()
                }
            }

            // Сlosure
            let clearValueAndMoveBack = {
                textField.text = ""
                let previousTag = textField.tag - 1
                if let previousResponder = textField.superview?.viewWithTag(previousTag) {
                    previousResponder.becomeFirstResponder()
                }
            }

            if textFieldCount < 1 && string.count > 0 {

                setValueAndMoveForward()

                if textField.tag == 4 {
                    print("Do something")
                }

                return false

            } else if textFieldCount >= 1 && string.count == 0 {

                clearValueAndMoveBack()
                return false

            } else if textFieldCount >= 1 {

                setValueAndMoveForward()
                return false
            }

            return true

        }

 }

Also, I implemented this feature:

In the case where the last textFiled is empty, I just want to switch to the previous textFiled. I tried all this methods. But as for me the method below more elegant and works like a charm:

Variant A

class EnterConfirmationCodeTextField: UITextField {

    // MARK: Life cycle

    override func awakeFromNib() {
        super.awakeFromNib()

        delegate = self
    }

    // MARK: Methods

    override func deleteBackward() {
        super.deleteBackward()

        let previousTag = self.tag - 1
        if let previousResponder = self.superview?.viewWithTag(previousTag) {
            previousResponder.becomeFirstResponder()

            if let activeTextField = previousResponder as? UITextField {
                if let isEmpty = activeTextField.text?.isEmpty, !isEmpty {
                    activeTextField.text = String()
                }
            }
        }
    }

}

Variant B (a little bit another behavior):

class EnterConfirmationCodeTextField: UITextField {

    // MARK: Life cycle

    override func awakeFromNib() {
        super.awakeFromNib()

        delegate = self
    }

    // MARK: Methods

    override func deleteBackward() {
        super.deleteBackward()

        let previousTag = self.tag - 1
        if let previousResponder = self.superview?.viewWithTag(previousTag) {
            previousResponder.becomeFirstResponder()
        }
    }

}

Assign EnterConfirmationCodeTextField for each of your textFields and set they appropriate tag value.

Answer 2

It can be achieve using UITextField delegate & by setting Tag for each Textfield in increasing order (say 1 - 4), below is the delegate handler to solve the issue.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
        // On inputing value to textfield
        if (textField.text?.characters.count < 1  && string.characters.count > 0){
            let nextTag = textField.tag + 1;

            // get next responder
            var nextResponder = textField.superview?.viewWithTag(nextTag);

            if (nextResponder == nil){
                nextResponder = textField.superview?.viewWithTag(1);
            }
            textField.text = string;
            nextResponder?.becomeFirstResponder();
            return false;
        }
        else if (textField.text?.characters.count >= 1  && string.characters.count == 0){
            // on deleteing value from Textfield
            let previousTag = textField.tag - 1;

            // get next responder
            var previousResponder = textField.superview?.viewWithTag(previousTag);

            if (previousResponder == nil){
                previousResponder = textField.superview?.viewWithTag(1);
            }
            textField.text = "";
            previousResponder?.becomeFirstResponder();
            return false;
        }
        return true;
    }

Answer 3

swift 2.3

      class BankDepositsWithOTPVC: UIViewController {

            let limitLength = 1  

        override func viewDidLoad() {
            super.viewDidLoad()
        }


        }

        // MARK: Textfield Validator

        extension BankDepositsWithOTPVC : UITextFieldDelegate {


            func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
                // On inputing value to textfield
                if (textField.text?.characters.count < 1  && string.characters.count > 0){
                    let nextTag = textField.tag + 1;

                    // get next responder
                    let nextResponder = textField.superview?.viewWithTag(nextTag);

                    if (nextResponder == nil){
                        textField.resignFirstResponder()
                      //  nextResponder = textField.superview?.viewWithTag(1);
                    }
                    textField.text = string;
                    nextResponder?.becomeFirstResponder();
                    return false;

                }else  if (textField.text?.characters.count >= 1  && string.characters.count > 0){
                                    // maximum 1 digit

textField.text = "";

                    let nextTag = textField.tag + 1;

                    // get next responder
                    let nextResponder = textField.superview?.viewWithTag(nextTag);

                    if (nextResponder == nil){
                        textField.resignFirstResponder()
                        //  nextResponder = textField.superview?.viewWithTag(1);
                    }
                    textField.text = string;
                    nextResponder?.becomeFirstResponder();
                    return false;
                }
                else if (textField.text?.characters.count >= 1  && string.characters.count == 0){
                    // on deleteing value from Textfield
                    let previousTag = textField.tag - 1;

                    // get next responder
                    var previousResponder = textField.superview?.viewWithTag(previousTag);

                    if (previousResponder == nil){
                        previousResponder = textField.superview?.viewWithTag(1);
                    }
                    textField.text = "";
                    previousResponder?.becomeFirstResponder();
                    return false;
                }
                //return true;

                guard let text = textField.text else { return true }
                let newLength = text.characters.count + string.characters.count - range.length
                return newLength <= limitLength

            }

        }

Objective-C

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{

    if ((textField.text.length < 1) && (string.length > 0))
    {

        NSInteger nextTag = textField.tag + 1;
        UIResponder* nextResponder = [textField.superview viewWithTag:nextTag];
        if (! nextResponder){
            [textField resignFirstResponder];
        }
        textField.text = string;
        if (nextResponder)
            [nextResponder becomeFirstResponder];

        return NO;

    }else if ((textField.text.length >= 1) && (string.length > 0)){
        //FOR MAXIMUM 1 TEXT

        NSInteger nextTag = textField.tag + 1;
        UIResponder* nextResponder = [textField.superview viewWithTag:nextTag];
        if (! nextResponder){
            [textField resignFirstResponder];
        }
        textField.text = string;
        if (nextResponder)
            [nextResponder becomeFirstResponder];

        return NO;
    }
    else if ((textField.text.length >= 1) && (string.length == 0)){
        // on deleteing value from Textfield

        NSInteger prevTag = textField.tag - 1;
        // Try to find prev responder
        UIResponder* prevResponder = [textField.superview viewWithTag:prevTag];
        if (! prevResponder){
            [textField resignFirstResponder];
        }
        textField.text = string;
        if (prevResponder)
            // Found next responder, so set it.
            [prevResponder becomeFirstResponder];

        return NO;
    }

      return YES;
}

Answer 4

Use this code if you don't want to work with tag and it works better then above

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        // On inputing value to textfield
        if ((textField.text?.characters.count)! < 1  && string.characters.count > 0){
            if(textField == txtOne)
            {
                txtTwo.becomeFirstResponder()
            }
            if(textField == txtTwo)
            {
                txtThree.becomeFirstResponder()
            }
            if(textField == txtThree)
            {
                txtFour.becomeFirstResponder()
            }

            textField.text = string
            return false
        }
        else if ((textField.text?.characters.count)! >= 1  && string.characters.count == 0){
            // on deleting value from Textfield
            if(textField == txtTwo)
            {
                txtOne.becomeFirstResponder()
            }
            if(textField == txtThree)
            {
                txtTwo.becomeFirstResponder()
            }
            if(textField == txtFour)
            {
                txtThree.becomeFirstResponder()
            }
            textField.text = ""
            return false
        }
        else if ((textField.text?.characters.count)! >= 1  )
        {
            textField.text = string
            return false
        }
        return true
    }

Answer 5

Swift 4

when you input a number from the pin code into a text field, you should let a number be shown and then the next text field will become the first responder, so change the first responder after the code was in the text view

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard let textField = textField as? PinCodeTextField else { return true }

    if string == "" {// when the backward clicked, let it go :)
        return true
    }

    // when textfield is not empty, well, next number
    if textField.pinCode.count == textField.maxCount {
        becomeFirstResponder(after: textField)
        return false
    }

    if string.count > textField.maxCharacterCount {// the max character count should be 1
        return false
    }
    return true
}
// now the text field has been filled with a number
func textFieldCotentDidChange(_ textField: UITextField) {
    print("didchange")
    guard let textField = textField as? PinCodeTextField else { return }
    if textField.pinCode.count == 0 {
        becomeFirstResponder(before: textField)
    }

    // when textfield has been filled, ok! next!
    if textField.pinCode.count == textField.maxCharacterCount {
        becomeFirstResponder(after: textField)
    }
}

for more details and the simple demo, see this link

Answer 6

Just use TextFieldDelegate method and check the length of the TextField after every changes

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    let newString = (textField.text! as NSString).stringByReplacingCharactersInRange(range, withString: string)
    if newString.characters.count == 1
    {
        nextTextField.becomeFirstResponder()
        return true
    }
    else
    {
        return false
    }
}