Allow only Numbers for UITextField input

IosIpadCocoa TouchUitextfieldUikeyboard

Ios Problem Overview

The iPad does not have a "Numpad" keyboard like the iPhone/iPod does.

I'm looking to find how I can restrict the user's keyboard to only accept values 0 through 9.

I would imagine using UITextField's "shouldChangeCharactersInRange" but I don't know the best way to implement it.

Ios Solutions

Solution 1 - Ios

This is how you might handle the problem on a SSN verification field, you can modify the max length and remove the if statement checking for keyboard type if you need to.

There is also logic to suppress the max length alerts when the user is typing as opposed to pasting data.

Within the context of this code, presentAlert()/presentAlert: is just some basic function that presents a UIAlertController (or a legacy UIAlertView) using the message string passed.

Swift 5

// NOTE: This code assumes you have set the UITextField(s)'s delegate property to the 
// object that will contain this code, because otherwise it would never be called.
//
// There are also some better stylistic approaches in Swift to avoid all the 
// nested statements, but I wanted to keep the styles similar to allow others 
// to contrast and compare between the two languages a little easier.

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

    // Handle backspace/delete
    guard !string.isEmpty else {

        // Backspace detected, allow text change, no need to process the text any further
        return true
    }

    // Input Validation
    // Prevent invalid character input, if keyboard is numberpad
    if textField.keyboardType == .numberPad {

        // Check for invalid input characters
        if CharacterSet(charactersIn: "0123456789").isSuperset(of: CharacterSet(charactersIn: string)) {

            // Present alert so the user knows what went wrong
            presentAlert("This field accepts only numeric entries.")

            // Invalid characters detected, disallow text change
            return false
        }
    }

    // Length Processing
    // Need to convert the NSRange to a Swift-appropriate type
    if let text = textField.text, let range = Range(range, in: text) {

        let proposedText = text.replacingCharacters(in: range, with: string)

        // Check proposed text length does not exceed max character count
        guard proposedText.count <= maxCharacters else {

            // Present alert if pasting text
            // easy: pasted data has a length greater than 1; who copy/pastes one character?
            if string.count > 1 {

                // Pasting text, present alert so the user knows what went wrong
                presentAlert("Paste failed: Maximum character count exceeded.")
            }

            // Character count exceeded, disallow text change
            return false
        }

        // Only enable the OK/submit button if they have entered all numbers for the last four
        // of their SSN (prevents early submissions/trips to authentication server, etc)
        answerButton.isEnabled = (proposedText.count == 4)
    }

    // Allow text change
    return true
}

Objective-C

// NOTE: This code assumes you have set the UITextField(s)'s delegate property to the 
// object that will contain this code, because otherwise it would never be called.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // Handle backspace/delete
    if (!string.length)
    {
        // Backspace detected, allow text change, no need to process the text any further
        return YES;
    }

    // Input Validation
    // Prevent invalid character input, if keyboard is numberpad
    if (textField.keyboardType == UIKeyboardTypeNumberPad)
    {
        if ([string rangeOfCharacterFromSet:[NSCharacterSet decimalDigitCharacterSet].invertedSet].location != NSNotFound)
        {
            [self presentAlert: @"This field accepts only numeric entries."];
            return NO;
        }
    }

    // Length Validation
    NSString *proposedText = [textField.text stringByReplacingCharactersInRange:range withString:string];

    // Check proposed text length does not exceed max character count
    if (proposedText.length > maxCharacters)
    {
        // Present alert if pasting text
        // easy: pasted data has a length greater than 1; who copy/pastes one character?
        if (string.length > 1)
        {
            // Pasting text, present alert so the user knows what went wrong
            [self presentAlert: @"Paste failed: Maximum character count exceeded."];
        }

        // Character count exceeded, disallow text change
        return NO;
    }
    
    // Only enable the OK/submit button if they have entered all numbers for the last four
    // of their SSN (prevents early submissions/trips to authentication server, etc)
    self.answerButton.enabled = (proposedText.length == maxCharacters);

    // Allow text change
    return YES;
}

Solution 2 - Ios

You can use this code to allow only number in textField.

Before that set delegate for textField

      textFieldName.delegate=self;

or

      [textFieldName setDelegate:self];

Than use this code to allow only digit to textField

      - (BOOL) textField: (UITextField *)theTextField shouldChangeCharactersInRange:(NSRange)range replacementString: (NSString *)string {
//return yes or no after comparing the characters

      // allow backspace
      if (!string.length)
      {
           return YES;
      }

      ////for Decimal value start//////This code use use for allowing single decimal value
      //    if ([theTextField.text rangeOfString:@"."].location == NSNotFound)
      //    {
      //        if ([string isEqualToString:@"."]) {
      //            return YES;
      //        }
      //    }
      //    else
      //    {
      //        if ([[theTextField.text substringFromIndex:[theTextField.text rangeOfString:@"."].location] length]>2)   // this allow 2 digit after decimal 
      //        {
      //            return NO;
      //        }
      //    }
      ////for Decimal value End//////This code use use for allowing single decimal value

      // allow digit 0 to 9
      if ([string intValue])
      {
            return YES;
      }

      return NO;
    }

Solution 3 - Ios

Try this to avoid textfield clearing issue

Swift 3.0

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    guard NSCharacterSet(charactersInString: "0123456789").isSupersetOfSet(NSCharacterSet(charactersInString: string)) else {
        return false
    }
    return true
}

Swift 4.0

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard CharacterSet(charactersIn: "0123456789").isSuperset(of: CharacterSet(charactersIn: string)) else {
        return false
    }
    return true
}

Solution 4 - Ios

Very specific steps for Swift code

You can provide logic that restricts the text field's input in the func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool method by implementing the UITextFieldDelegate protocol.

For the sake of clarity, these steps assume that your storyboard contains a View Controller with a text field object that should only accept digits.

  1. Create a custom class for the view controller that extends UIViewController. Make sure that the scene in your storyboard refers to the custom class by setting the custom class value in Xcode's Identity Inspector.

     import UIKit
 class YourCustomController: UIViewController {
     override func viewDidLoad() {        
         super.viewDidLoad()
     }
 }

  2. Create an outlet from your scene's text field to your custom View Controller.

     class YourCustomController: UIViewController {
     @IBOutlet weak var numberField: UITextField!
     ...
 }

  3. Apply the UITextFieldDelegate protocol in your custom view controller.

     class YourCustomController: UIViewController, UITextFieldDelegate {
     ...
 }

  4. In your custom view controller's viewDidLoad method, assign your text field's delegate to your custom view controller class.

     override func viewDidLoad() {        
     super.viewDidLoad()
     numberField.delegate = self
 }

  5. Add the UITextFieldDelegate's func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool method.

    As a result of making your custom view controller the numberField's delegate in the previous step, this method will be called each time a user enters a character into the text field. If your method returns true then the character will remain in the text field. If your method returns false then the character will not remain in the text field.

    The string parameter is the character being entered by the user. If the string character can be converted to an Int then it is between 0 and 9; otherwise, it is some non-number character.

     class YourCustomController: UIViewController, UITextFieldDelegate {
     ...
     func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

         return Int(string) != nil
     }
 }

(See below for the full view controller code.)

Example View Controller with digits only text field

import UIKit

class YourCustomController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var numberField: UITextField!

    override func viewDidLoad() {        
        super.viewDidLoad()       
        numberField.delegate = self
    }

    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {        
        return Int(string) != nil
    }    
}

Example View Controller with a Decimal text field

If you want to support a decimal number then take advantage of NSNumberFormatter. See the code comments for the differences.

import UIKit

class YourCustomController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var numberField: UITextField!

    private var formatter: NSNumberFormatter!

    override func viewDidLoad() {        
        super.viewDidLoad()       
        numberField.delegate = self

        // Initialize the formatter; minimum value is set to zero; style is Decimal. 
        formatter = NSNumberFormatter()
        formatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
        formatter.minimum = 0
    }

    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
        // Combine the current text field value and the new string
        // character. If it conforms to the formatter's settings then
        // it is valid. If it doesn't then nil is returned and the
        // string character should not be allowed in the text field.         
        return formatter.numberFromString("\(textField.text)\(string)") != nil
    }    
}

Solution 5 - Ios

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

    NSNumberFormatter * nf = [[NSNumberFormatter alloc] init];
    [nf setNumberStyle:NSNumberFormatterNoStyle];

    NSString * newString = [NSString stringWithFormat:@"%@%@",textField.text,string];
    NSNumber * number = [nf numberFromString:newString];

    if (number)
        return YES;
    else
       return NO;
}

Solution 6 - Ios

I applied this and it works!!

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    // Check for non-numeric characters
    NSUInteger lengthOfString = string.length;
    for (NSInteger index = 0; index < lengthOfString; index++) {
        unichar character = [string characterAtIndex:index];
        if (character < 48) return NO; // 48 unichar for 0
        if (character > 57) return NO; // 57 unichar for 9
    }
    // Check total length for restrict user
    NSUInteger proposedNewLength = textField.text.length - range.length + string.length;
    if (proposedNewLength > 6)
        return YES;
    return YES;                                                                                                                                     
}

Solution 7 - Ios

swift 5

    //MARK:- UITextFieldDelegate

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    
    let allowedCharacters = "1234567890"
    let allowedCharcterSet = CharacterSet(charactersIn: allowedCharacters)
    let typedCharcterSet = CharacterSet(charactersIn: string)
    return allowedCharcterSet.isSuperset(of: typedCharcterSet)
}

You can now just tap 1234567890 only

Solution 8 - Ios

NSString* val = [[textField text] stringByReplacingCharactersInRange:range withString:string];
    NSCharacterSet *allowedCharacterSet = [NSCharacterSet decimalDigitCharacterSet];
    if ([[string componentsSeparatedByCharactersInSet:[allowedCharacterSet invertedSet]] count] > 1 || [val length] > 5) {
        return NO;
    }

Solution 9 - Ios

Works fine for me :

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (([string rangeOfCharacterFromSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]].location != NSNotFound) && !(range.length==1 && string.length==0)) {
            return NO;
        }
        return YES;
    }

Solution 10 - Ios

In Swift:

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        return string.isEmpty || Int(string) != nil
    }

Solution 11 - Ios

Keep distinct presentation data from internal representation. There is a simpler way. Let NSNumberFormatter do the job:

 NSNumberFormatter* ns = [[NSNumberFormatter alloc] init];
 ns.numberStyle = NSNumberFormatterDecimalStyle;
 [ns setMaximumFractionDigits:2];
 // This is your internal representation of the localized number
 double a = [[ns numberFromString:self.textIVA.text] doubleValue]];

[mylabel setText:[NSString stringWithFormat:@"€ %@",
     [NSNumberFormatter localizedStringFromNumber:
                          [NSNumber numberWithDouble:a]
                                      numberStyle:NSNumberFormatterDecimalStyle]]];

Solution 12 - Ios

I have modified @iDev's answer to work for digitals and ".":

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
     // Check for non-numeric characters
     NSUInteger lengthOfString = string.length;
     for (NSInteger index = 0; index < lengthOfString; index++) {
         unichar character = [string characterAtIndex:index];
         if ((character < 48) && (character != 46)) return NO; 
         // 48 unichar for 0, and 46 unichar for point
         if (character > 57) return NO; 
         // 57 unichar for 9
     }
     // Check for total length
     NSUInteger proposedNewLength = textField.text.length - range.length + string.length;
     if (proposedNewLength > 6)
         return YES;
     return YES; 
 }

Solution 13 - Ios

If you use my specification pattern then code looks like this

textField.delegate = self

lazy var specification: Specification = {
	return RegularExpressionSpecification(pattern: "^(|0|[1-9]\\d{0,6})$")
}()

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
	let textFieldString: NSString = textField.text ?? ""
	let s = textFieldString.stringByReplacingCharactersInRange(range, withString:string)
	return specification.isSatisfiedBy(s)
}

func textFieldShouldReturn(textField: UITextField) -> Bool {
	let s = textField.text ?? ""
	let isTextValid = specification.isSatisfiedBy(s)
	if isTextValid {
		textField.resignFirstResponder()
	}
	return false
}

Solution 14 - Ios

swift 3

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField==yourTextFieldOutlet {
                if(CharacterSet.decimalDigits.isSuperset(of: CharacterSet(charactersIn: yourTextFieldOutlet.text!))){
//if numbers only, then your code here
                }
                else{
                showAlert(title: "Error",message: "Enter Number only",type: "failure")
                }
            }
    return true
    }

Solution 15 - Ios

Use this code:

NSString* val = [[textField text] stringByReplacingCharactersInRange:range withString:string];
NSCharacterSet *allowedCharacterSet = [NSCharacterSet decimalDigitCharacterSet];
if ([[string componentsSeparatedByCharactersInSet:[allowedCharacterSet invertedSet]] count] > 1 || [val length] > 5) {
    return NO;
}
Categories
Recommended Ios Solutions
Recommended Ipad Solutions
Recommended Cocoa Touch Solutions
Recommended Uitextfield Solutions
Recommended Uikeyboard Solutions

Previous Solution:

Creating layout constraints programmatically

Objective CIosConstraintsAutolayout

Next Solution:

Twitter Bootstrap Datepicker within modal window

JqueryTwitter BootstrapDatepicker

Attributions

All content for this solution is sourced from the original question on Stackoverflow.

The content on this page is licensed under the Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionDemasterplView Question on Stackoverflow
Solution 1 - IosBeltalowdaView Answer on Stackoverflow
Solution 2 - IosAjeView Answer on Stackoverflow
Solution 3 - IosSPatelView Answer on Stackoverflow
Solution 4 - IoswhyceewhiteView Answer on Stackoverflow
Solution 5 - IosBlazej SLEBODAView Answer on Stackoverflow
Solution 6 - IosiDevView Answer on Stackoverflow
Solution 7 - IosYounes IdrissiView Answer on Stackoverflow
Solution 8 - IosjohnnyView Answer on Stackoverflow
Solution 9 - IosAnkit Kumar GuptaView Answer on Stackoverflow
Solution 10 - IosmishimayView Answer on Stackoverflow
Solution 11 - IosgdmView Answer on Stackoverflow
Solution 12 - IosDarius MiliauskasView Answer on Stackoverflow
Solution 13 - IosneoneyeView Answer on Stackoverflow
Solution 14 - IosArgaPKView Answer on Stackoverflow
Solution 15 - Iosuser7592089View Answer on Stackoverflow