Allowing single digit in UITextField in iOS

2019-01-14 03:34发布

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问题:

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 like this

As you can see four UITextFields, I need to allow only single digit for each UITextField,

What I tried: I was trying to use shouldChangeCharactersInRange:method: , but its not getting called, I don't know what's wrong, I think because UITextFields are in UITableView so it is not working.

回答1:

You can change the text field like this by using the delegate function of the text field. Initially, you need to set the delegate and the tag of each text field.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if ((textField.text.length >= 1) && (string.length > 0))
    {
        NSInteger nextTag = textField.tag + 1;
        // Try to find next responder
        UIResponder* nextResponder = [textField.superview viewWithTag:nextTag];
        if (! nextResponder)
            nextResponder = [textField.superview viewWithTag:1];

        if (nextResponder)
           // Found next responder, so set it.
           [nextResponder becomeFirstResponder];

        return NO;
    }
    return YES;
}

Swift 2

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 deleting 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;
}

Swift 4

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    if textField.text!.count < 1  && string.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!.count >= 1  && string.count == 0{
        // on deleting 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

}


回答2:

use this code if you don't want 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
    }


回答3:

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;
    }


回答4:

I have taken one Hidden text field & four imageViews for that with two images. One for Blank and other for Bullet same as iOS default.

Also set tags for four imageviews.

On Load set Focus for Pin Code

- (void)startPinCode
{
    txtPinCodeLockDigits.text = @"";

    for (int i = 1; i <= 4; i++) {

       UIImageView *img = (UIImageView *)[self.view viewWithTag:i];
       [img setImage:[UIImage imageNamed:@"Img_BG_PinCode.png"]];
    }

    [txtPinCodeLockDigits becomeFirstResponder];
}

Then change imageview's images as per user input and only allow four characters

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSString *result = [textField.text stringByReplacingCharactersInRange:range withString:string];
    textField.text = result;

    for (int i = 1; i <= 4; i++) {

       UIImageView *img = (UIImageView *)[self.view viewWithTag:i];
       if (i <= [result length])
           [img setImage:[UIImage imageNamed:@"Img_BG_PinCode_Filled.png"]];
       else
           [img setImage:[UIImage imageNamed:@"Img_BG_PinCode.png"]];
     }

     NSLog(@"Result :: %@", result);

     if ([result length] == 4) {
        [self performSelector:@selector(keyGenerationForApplication:) withObject:result afterDelay:0.2];
     }

     return NO;
}

After Four characters call function for generated PIN Code and store it in User Defaults same as iOS default PIN settings

- (void)keyGenerationForApplication:(NSString *)pinCode
{
     int appCode = [pinCode intValue];
     [DefaultsValues setIntegerValueToUserDefaults:appCode ForKey:PIN_LOCK_PATTERN];
}

Here, you can again call StartPinCode method for re-confirming code.

Hopefully, it'll help you.
Thanks



回答5:

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;
}


回答6:

Provide the tag to the textfield like 1,2,3,4 and directly use it

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool


    let next:NSInteger

    if string == "" {

        next = textField.tag - 1;

    }
    else{

        next = textField.tag + 1;

    }

    if (textField.text?.characters.count)! >= 1 {

        if textField.tag == 4 {

            if string == "" {

                textField.text = ""

                let temptf = self.view.viewWithTag(next) as! UITextField

                temptf.becomeFirstResponder()

                return false

            }
            else{

                if (textField.text?.characters.count)! > 1 {

                    let stringg = textField.text!
                    textField.text = stringg.replacingOccurrences(of: stringg, with: string)
                }
                return false
            }
        }
        else{
            if string == "" {

                textField.text = ""

                if next != 0 {

                    let temptf = self.view.viewWithTag(next) as! UITextField
                    temptf.becomeFirstResponder()

                }

                return false
            }

            else{

                if (textField.text?.characters.count)! > 1 {


                    let stringg = textField.text!
                    textField.text = stringg.replacingOccurrences(of: stringg, with: string)

                }

                    let temptf = self.view.viewWithTag(next) as! UITextField

                    temptf.becomeFirstResponder()

            }
        }
    }

    return true

}


回答7:

Try this sample tutorial passcode lock

ViewController.h

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController<UITextFieldDelegate>
{
 IBOutlet UITextField *txtPassword;
}
 @end

ViewController.m

- (void)viewDidLoad
{
[super viewDidLoad];
txtPassword.delegate=self;
}


- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string 
{
NSUInteger newLength = [textField.text length] + [string length] - range.length;
return (newLength > 1) ? NO : YES;
}


回答8:

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.



回答9:

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



回答10:

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
    }
}


回答11:

Modified Anurag Soni's answer in Swift 3.

  • It assumes you have outlet collection named textFields and the text fields have ordered tags set
  • It adds case when there's already some digit in text field and when user types something new - the digit is replaced
  • Input is restricted to digits only

  • It prevents from pasting more than one digit

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // Restrict to only digits
    let aSet = NSCharacterSet(charactersIn:"0123456789").inverted
    let compSepByCharInSet = string.components(separatedBy: aSet)
    let numberFiltered = compSepByCharInSet.joined(separator: "")

    if string != numberFiltered {
        return false
    }

    // Get the unwrapped text
    guard let text = textField.text else {
        return false
    }

    if (text.characters.count < 1  && string.characters.count == 1) {
        // New value to empty text field
        textField.text = string

        // Next responder
        if let someTextField = (textFields.filter { $0.tag == textField.tag + 1 }).first {
            someTextField.becomeFirstResponder()
        } else {
            view.endEditing(true)
        }

        return false
    } else if (text.characters.count >= 1  && string.characters.count == 0){
        // On deleting value from Textfield
        textField.text = ""

        // Previous responder
        if let someTextField = (textFields.filter { $0.tag == textField.tag - 1 }).first {
            someTextField.becomeFirstResponder()
        } else {
            view.endEditing(true)
        }

        return false
    } else if string.characters.count == 1 {
        // There's already some digit in text field
        // Replace it with new one
        textField.text = string

        // Next responder
        if let someTextField = (textFields.filter { $0.tag == textField.tag + 1 }).first {
            someTextField.becomeFirstResponder()
        } else {
            view.endEditing(true)
        }
    }

    return false
}


回答12:

I was working on a similar functionality and did it in my way. Solution below. Swift 4

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

 //For clear button pressed
 //If the textfield has already text in it
 if string.count == 0 {
    textField.text = string
    return true
 }

 //For First time entry into the text field
 guard let text = textField.text, text.count <= 0  else {
    //If user enter second character
    return false
 }
 //For First time entry into the text field
 if text.count == 0  {
     textField.text = string
     textField.resignFirstResponder()
     self.nextResponde(tag: textField.tag)
     return true
  }
  return false
}

//To make the next field as responder
func nextResponde(tag: Int) {
    switch tag {
    case self.PINTextField.tag:
        guard let text = self.PINTextField1.text, text.count == 1 else {
            self.PINTextField1.becomeFirstResponder()
            return
        }
    case self.PINTextField1.tag:
        guard let text = self.PINTextField2.text, text.count == 1 else {
            self.PINTextField2.becomeFirstResponder()
            return
        }
    case self.PINTextField2.tag:
        guard let text = self.PINTextField3.text, text.count == 1 else {
            self.PINTextField3.becomeFirstResponder()
            return
        }
    default:
        let _ = tag
    }
}


回答13:

try this : - For swift 3.0

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){
        let nextTag = textField.tag + 1;

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

        if (nextResponder == nil){
            textField.resignFirstResponder()
        }
        nextResponder?.becomeFirstResponder();
        return false;
    }
    else if ((textField.text?.characters.count)! >= 1  && string.characters.count == 0){
        // on deleting 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;
}

converted Anurag Soni answer in swift 3.0

You just have to implement this method only.



标签： ios objective-c swift uitableview uitextfield
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