UITextField Should accept number only values

Question

I have UITexfields i want that it should accept only number other shows alert that enter a numeric value. I want that motionSicknessTextFiled should only accept number

Answer 1

Here is the working example for swift 4

public func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
{
    // Allow Backspace
    if string.count == 0 {
        return true
    }

    // Allow Only Valid Decimal Numbers
    if let textFieldText = textField.text   {

        let finalText = (textFieldText as NSString).replacingCharacters(in: range, with: string)
        if Double(finalText) != nil {
            return true
        }
    }
    return false
}

Answer 2

Swift

class ExampleVC: UIViewController {

    let numbers = "0123456789";

    override func viewDidLoad() {
        super.viewDidLoad()

        let textfield = UITextField(frame: CGRectMake(20, 100, 300, 44))
        //make some customization, if you want
        self.view.addSubview(textfield)

        textfield.delegate = self;
    }
}

extension ExampleVC: UITextFieldDelegate {

    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        return string.characters.count > 0 ? numbers.contains(string) : true
    }
}

Answer 3

This answer threw some error in Swift 3, here's the working answer:

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string.characters.count == 0 {
        return true
    }
    do {
        if textField == self.numberTextField {

            let nString = textField.text as NSString?
            let newString = nString?.replacingCharacters(in: range, with: string)
            let expression = "^([0-9]+)?(\\.([0-9]{1,2})?)?$"
            let regex = try NSRegularExpression(pattern: expression, options: .caseInsensitive)
            let numberOfMatches = regex.numberOfMatches(in: newString! as String, options: [], range: NSRange(location: 0, length: (newString?.characters.count)!))

            if numberOfMatches == 0 {
                return false
            }
        }
    }
    catch let error {
    }
    return true
}

Answer 4

In whatever UITextField you're getting these values from, you can specify the kind of keyboard you want to appear when somebody touches inside the text field.

E.G. a numeric-only keyboard.

Like this screenshot:

This is easily set when working with the XIB and the Interface Builder built into Xcode, but if you want to understand this programmatically, take a look at Apple's UITextInputTraits protocol reference page, specifically the keyboardType property information.

To filter out punctuations, set the textfield's delegate and set up the shouldChangeCharactersInRange method:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
    NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:textField.text];

    BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
    return stringIsValid;
}

Answer 5

I've implemented the snippet which has the features for textField:

1. Check the maximum allowed characters.
2. Check the valid decimal number.
3. Check only numeric numbers.

The code is the UITextField delegate method. Before you use this snippet, you must have these properties:

1. self.maxCharacters
2. self.numeric // Only int characters.
3. self.decimalNumeric // Only numbers and ".", "," (for specific locales, like Russian).

Code:

- (BOOL)textField:(UITextField *) textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if(self.numeric || self.decimalNumeric)
    {
        NSString *fulltext = [textField.text stringByAppendingString:string];
        NSString *charactersSetString = @"0123456789";

        // For decimal keyboard, allow "dot" and "comma" characters.
        if(self.decimalNumeric) {
            charactersSetString = [charactersSetString stringByAppendingString:@".,"];
        }

        NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:charactersSetString];
        NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:fulltext];

        // If typed character is out of Set, ignore it.
        BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
        if(!stringIsValid) {
            return NO;
        }

        if(self.decimalNumeric)
        {
            NSString *currentText = [textField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];

            // Change the "," (appears in other locale keyboards, such as russian) key ot "."
            currentText = [currentText stringByReplacingOccurrencesOfString:@"," withString:@"."];

            // Check the statements of decimal value.
            if([fulltext isEqualToString:@"."]) {
                textField.text = @"0.";
                return NO;
            }

            if([fulltext rangeOfString:@".."].location != NSNotFound) {
                textField.text = [fulltext stringByReplacingOccurrencesOfString:@".." withString:@"."];
                return NO;
            }

            // If second dot is typed, ignore it.
            NSArray *dots = [fulltext componentsSeparatedByString:@"."];
            if(dots.count > 2) {
                textField.text = currentText;
                return NO;
            }

            // If first character is zero and second character is > 0, replace first with second. 05 => 5;
            if(fulltext.length == 2) {
                if([[fulltext substringToIndex:1] isEqualToString:@"0"] && ![fulltext isEqualToString:@"0."]) {
                    textField.text = [fulltext substringWithRange:NSMakeRange(1, 1)];
                    return NO;
                }
            }
        }
    }

    // Check the max characters typed.
    NSUInteger oldLength = [textField.text length];
    NSUInteger replacementLength = [string length];
    NSUInteger rangeLength = range.length;

    NSUInteger newLength = oldLength - rangeLength + replacementLength;
    BOOL returnKey = [string rangeOfString: @"\n"].location != NSNotFound;

    return newLength <= _maxCharacters || returnKey;
}

Demo:

Answer 6

Modified Michael Dautermann's answer:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if(string.length > 0)
    {
        NSCharacterSet *numbersOnly = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
        NSCharacterSet *characterSetFromTextField = [NSCharacterSet characterSetWithCharactersInString:string];

        BOOL stringIsValid = [numbersOnly isSupersetOfSet:characterSetFromTextField];
        return stringIsValid;
    }
    return YES;
}