swift - 'substring(to:)' is deprecated: Please use String slicing subscript with a 'partial range upto' operator

Question

How can I update the following code to the new version of swift:

self.areaCodeLael.text! = localNumber.substring(to: localNumber.index(localNumber.startIndex, offsetBy: 3))

I have tried following this post but I can't get it right How can I use String slicing subscripts in Swift 4?

I adjusted my original code to localNumber[..<3] but I get:

Cannot subscript a value of type 'String' with an index of type 'PartialRangeUpTo'

Answer 1

I would say localNumber.prefix(3) in this situation. Short and sweet.