Argument type 'String?' does not conform to expected type 'StringProtocol'

Question

This error occurs when using compare on a String in Swift 5 , it accepts only StringProtocol , but I want to use it on String and can't find nowhere how to do it.

I've searched all over and can't understand what seems to be the issue.

Answer 1

Problem that Optional<String> (aka String? ) is not conform to StringProtocol (and that makes sense). You should unwrap optional, there is several ways:

1. Unwrapping by if let / guard ( if let version = dbData?.version { //compare } )
2. Providing default value ( `(dbData?.version ?? "")), which is not recommended, because it can provide unnecessary collisions
3. Force unwrap dbData!.version , which is highly not recommended, because it can involve crashing an app, if Optional was nil