Where is rawValue defined in Color(rawValue)?

Question

I'm trying to follow this tutorial on iOS app development and I don't understand how or where rawValue gets defined in the 3rd last line in this statement

import SwiftUI

enum Theme: String {
    case bubblegum
    case buttercup
    case indigo
    case lavender
    case magenta
    case navy
    case orange
    case oxblood
    case periwinkle
    case poppy
    case purple
    case seafoam
    case sky
    case tan
    case teal
    case yellow

    var accentColor: Color {
        switch self {
        case .bubblegum, .buttercup, .lavender, .orange, .periwinkle, .poppy, .seafoam,
             .sky, .tan, .teal, .yellow: return .black
        case .indigo, .magenta, .navy, .oxblood, .purple: return .white
        }
    }

    var mainColor: Color {
        Color(rawValue)
    }
}

I understand that rawValue is a property of a case in an enumeration so presumably rawValue will point to some string associated with a case defined above.

But, how does is know which case we are using for mainColor? The property doesn't refer to self as in accentColor.

Also, it appears that this is a calculated property with no setter, so it's not getting set at run time either (not that the argument is named anyways)

Is rawValue defined somewhere in the import SwiftUI? If so, why?

Answer 1

mainColor is an instance computed property. self is implied, but it can be explicitly stated. That is the code could say:

var mainColor: Color {
   Color(self.rawValue)
}

Omitting self is idiomatically common.

Just as in accentColor, self will be a particular case. That is, each case has a mainColor and a corresponding accentColor. There isn't a single mainColor for Theme.

In use you would say something like Theme.bubblegum.mainColor.

The actual value of rawvalue will be a String equivalent to the case name - this is generated because the enum declaration specifies a String raw type but no explicit raw value is provided.