SwiftUI：自定义字符串类型

Question

I've just started learning SwiftUI, so I'm very new to framework and know very little about the Swift language in general. I'm trying to figure out how to define a custom type.

I've got a @State variable that can be one of three strings ( "OFF" , "ON" , "ONCE" ).

This is what I have so far:

@State private var mode: String = "OFF"

The problem is, I would like to enforce this variable to conform to a "stricter" type instead of simply setting it to String .

Something akin to this maybe... (I realise this isn't valid, but I'm coming from a TypeScript world so please forgive me)

type Mode = "OFF" | "ON" | "ONCE"

@State private var mode: Mode = "OFF"

Any help would be appreciated. Thanks in advance!

Answer 1

You should use an enum

enum Mode: String {
    case on = "ON"
    case off = "OFF"
    case once = "ONCE"
}

Enum in Swift are really powerful, check the complete guide here: Enumerations