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Hao's Keeper

A blog to place memos

• on swift

Enum Implicitly Assigned Raw Values

Associated Values

enum productBarcode {
	case upc(Int, Int, Int, Int)
	case qrCode(String)
}

var productBarcode = .qrCode("ABCDEFG")

switch productBarcode {
	case .upc(let numberSystem, let manufacturer, let product, let check):
		print("UPC: \(numberSystem), \(manufacturer), \(product), \(check)")
	
	// if all are variables or costants, place var or let before the case name, for brevity:  
	case let .qrCode(productCode):
		print("QR code: \(productCode)")
}

Raw values are not the same as associated values.

Raw values are set to prepopulated values when you first define the enumeration in your code.
The raw value for a particular enumeration case is always the same.

Associated values are set when you create a new constant or variable based on one of the enumeration’s cases, and can be different each time you do so.

enum Planet: Int {
    case mercury = 1, venus, earth, mars, jupiter, saturn, uranus, neptune
}

Planet.venus has an implicit raw value of 2, and so on.

When strings are used for raw values, the implicit value for each case is the text of that case’s name.

enum CompassPoint: String {
    case north, south, east, west
}

CompassPoint.south has an implicit raw value of “south”, and so on.

rawValue property

let earthsOrder = Planet.earth.rawValue
// earthsOrder is 3

let sunsetDirection = CompassPoint.west.rawValue
// sunsetDirection is "west"

let possiblePlanet = Planet(rawValue: 7)
// possiblePlanet is of type Planet? and equals Planet.uranus