Restrict NSTextField to only allow numbers

Question

How do I restrict a NSTextfield to allow only numbers/integers? I\'ve found questions like this one, but they didn\'t help!

Answer 1

Swift 2.0 custom formatter with 0 instead of empty space :

class OnlyIntegerValueFormatter: NSNumberFormatter {

    override func isPartialStringValid(partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>) -> Bool {

        if partialString.isEmpty {
            newString.memory = "0"
            return false
        }

        if Int(partialString) < 0 {
            NSBeep()
            return false
        } else {
            return true
        }
    }
}

Answer 2

In SWIFT, I do it this way

1. Convert the text value to Int with Int()
2. Check the converted value is not less than 0

3. If less than 0, display error message other accept the value

   if ((Int(txtField.stringValue)) < 0){
       // Display error message
   }
   

Answer 3

[Works with Swift 3.0.1]

As others suggested, subclass NumberFormatter and override isPartialStringValid method. The easiest way is to drop a NumberFormatter object under your NSTextField in xib/storyboard and update it's Custom Class. Next implementation allows only integers or blank value and plays a beep if string contains illegal characters.

class IntegerFormatter: NumberFormatter {

    override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {

        // Allow blank value
        if partialString.numberOfCharacters() == 0  {
            return true
        }

        // Validate string if it's an int
        if partialString.isInt() {
            return true
        } else {
            NSBeep()
            return false
        }
    }
}

String's numberOfCharacters() and isInt() are methods added in an extension.

extension String {

    func isInt() -> Bool {

        if let intValue = Int(self) {

            if intValue >= 0 {
                return true
            }
        }

        return false
    }

    func numberOfCharacters() -> Int {
        return self.characters.count
    }
}

Answer 4

Here is the steps to create the same....

Just create the ANYCLASS(called SAMPLE) with sub classing the NSNumberFormatter ...

in .m file write the following code...

 - (BOOL)isPartialStringValid:(NSString *)partialString newEditingString:(NSString      **)newString errorDescription:(NSString **)error {
// Make sure we clear newString and error to ensure old values aren't being used
if (newString) { *newString = nil;}
if (error) {*error = nil;}

static NSCharacterSet *nonDecimalCharacters = nil;
if (nonDecimalCharacters == nil) {
    nonDecimalCharacters = [[NSCharacterSet decimalDigitCharacterSet] invertedSet] ;
}

if ([partialString length] == 0) {
    return YES; // The empty string is okay (the user might just be deleting everything and starting over)
} else if ([partialString rangeOfCharacterFromSet:nonDecimalCharacters].location != NSNotFound) {
    return NO; // Non-decimal characters aren't cool!
}

return YES;

}

Now.. in your Actual Class set the formatter to your NSTextField object like below...

NSTextField *mySampleTxtFld;

for this set the Formatter...

SAMPLE* formatter=[[SAMPLE alloc]init];// create SAMPLE FORMATTER OBJECT 

self.mySampleTxtFld.delegate=self;
[self.mySampleTxtFld setFormatter:formatter];

Your done!!!

Answer 5

Here is a Swift version:

override func isPartialStringValid(partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>) -> Bool {
    if (count(partialString.utf16)) {
        return true
    }

    if (partialString.rangeOfCharacterFromSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet) != nil) {
        NSBeep()
        return false
    }

    return true
}

Answer 6

Swift 3 Version

import Foundation

    class OnlyIntegerValueFormatter: NumberFormatter {

    override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {

        // Ability to reset your field (otherwise you can't delete the content)
        // You can check if the field is empty later
        if partialString.isEmpty {
            return true
        }

        // Optional: limit input length
        /*
        if partialString.characters.count>3 {
            return false
        }
        */

        // Actual check
        return Int(partialString) != nil
    }
}

Use:

let onlyIntFormatter = OnlyIntegerValueFormatter()
myNsTextField.formatter = onlyIntFormatter