How to convert english numbers inside a string to Persian/Arabic numbers in Objective-C?

Question

I have an english string that may or may not have numbers. But i want those numbers to be printed on screen as Persian numbers.

For example if NSString *foo =

Answer 1

In swift 3:

func convertEngNumToPersianNum(num: String)->String{
    let number = NSNumber(value: Int(num)!)
    let format = NumberFormatter()
    format.locale = Locale(identifier: "fa_IR")
    let faNumber = format.string(from: number)

    return faNumber!
}

Check before force unwrap to prevent crash.