The thing is, each string-related answer ended up extending it with some methods that everyone wanted it to have in the first place, and the top-voted comments are like "why do we have to do this." It also shouldn't have required multiple updates to each answer.

The time I was doing a lot of string manipulation in a team Swift project, we had to write our own wrapper that basically stored strings as arrays of printable characters because the native one was too annoying. This also protected us from all the breaking changes Apple made to strings across Swift versions.

The inout one is different. It's confusing that arrays and dicts are structs, which have different rules from regular objects, and the syntax takes some getting used to:

  func addItem(_ localArr: inout [Int]) {
    localArr.append(4)
  }