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 3 Version

import Foundation

    class OnlyIntegerValueFormatter: NumberFormatter {

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