Set the maximum character length of a UITextField

Question

How can I set the maximum amount of characters in a UITextField on the iPhone SDK when I load up a UIView?

Answer 1

Swift 2.0 +

First of all create a class for this process. Lets call it StringValidator.swift.

Then just paste the following code inside it.

import Foundation

extension String {

func containsCharactersIn(matchCharacters: String) -> Bool {
let characterSet = NSCharacterSet(charactersInString: matchCharacters)
return self.rangeOfCharacterFromSet(characterSet) != nil
}

func containsOnlyCharactersIn(matchCharacters: String) -> Bool {
let disallowedCharacterSet = NSCharacterSet(charactersInString: matchCharacters).invertedSet
return self.rangeOfCharacterFromSet(disallowedCharacterSet) == nil
}


func doesNotContainCharactersIn(matchCharacters: String) -> Bool {
let characterSet = NSCharacterSet(charactersInString: matchCharacters)
return self.rangeOfCharacterFromSet(characterSet) == nil
}

func isNumeric() -> Bool
{
let scanner = NSScanner(string: self)
scanner.locale = NSLocale.currentLocale()

return scanner.scanDecimal(nil) && scanner.atEnd
}

}

Now save the class.....

Usage..

Now goto your viewController.swift class and make your textfield's outlets as..

@IBOutlet weak var contactEntryTxtFld: UITextField! //First textfield
@IBOutlet weak var contactEntryTxtFld2: UITextField!   //Second textfield

Now goto the textfield's shouldChangeCharactersInRange method and use like the following.

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    if string.characters.count == 0 {
        return true
    }
    let latestText = textField.text ?? ""
    let checkAbleText = (latestText as NSString).stringByReplacingCharactersInRange(range, withString: string)


    switch textField {

    case contactEntryTxtFld:
        return checkAbleText.containsOnlyCharactersIn("0123456789") && prospectiveText.characters.count <= 5

    case contactEntryTxtFld2:
        return checkAbleText.containsOnlyCharactersIn("0123456789") && prospectiveText.characters.count <= 5

    default:
        return true
    }

}

Don't forget to set the delegate protocol/methods of textfields.

Let me explain about this... I am using the simple extension process of string which I wrote inside an another class. Now I am just calling those extension methods from another class where I need them by adding check and maximum value.

Features...

1. It will set maximum limit of a particular textfield.
2. It will set type of accepted keys for particular textfield.

Types...

containsOnlyCharactersIn //Accepts only Characters.

containsCharactersIn //Accepts combination of characters

doesNotContainsCharactersIn //Will not accept characters

Hope this helped.... Thanks..