Where is the String interpolation from "Structure your app for SwiftUI previews" documented?

Question

Jessy OP

Created Jun ’20

Replies 1

Boosts 0

Participants 2

I'd never seen this before. (This is an image I can't upload.)

How are you supposed to format this?

Code Block swiftText(
  """
  \(
    { var nameComponents = PersonNameComponents()
      nameComponents.givenName = "Given"
      nameComponents.familyName = "Family"
      return nameComponents as NSPersonNameComponents
    } (),
    formatter: {
      let formatter = PersonNameComponentsFormatter()
      formatter.style = .long
      return formatter
    } ()
  )
  """
)

Boost

Answer 1

Developer Tools Engineer OP

Apple

Jun ’20

If you’re referring to the \(..., formatter: ...) interpolation syntax, this is one of the overloads of SwiftUI.LocalizedStringKey.StringInterpolation.appendInterpolation. Each of the overloads on that page is a different way you can use string interpolation in a localized SwiftUI string.

If you’re referring to the { ... }() syntax used for the parameters, that’s actually just a closure that gets called immediately after it’s formed. It’s a trick folks use to group together several statements into a single expression.

If you’re referring to the ””” syntax, that’s a multiline string literal. There’s a section about them in The Swift Programming Language.

The whole thing put together is just a combination of many slightly unusual language features.

0