在Swift中访问数组中枚举的rawValue

Question

I'm trying to use maxElement to work with enums in an array, accessed by .rawValue as shown in the example below:

var planets: [Planets] = [.Mars, .Earth, .Jupiter]
maxElement(planets.rawValue)

I could just use other methods to get the max rawValue but it would be so nice and easy if it could be used this way, but is it even possible?

Answer 1

There is no direct way to that.

let maxPlanet = Planets(rawValue: maxElement(planets.map({$0.rawValue})))!

You have to:

1. make an array of rawValue s
2. get maxElement from that.
3. convert back to enum using Planets(rawValue:)

Answer 2

Conform to Comparable protocol to use maxElement with your enum.

enum Planets: Int, Comparable {
    case Earth, Mars, Jupiter
}

func <(lhs: Planets, rhs: Planets) -> Bool {
    return lhs.rawValue < rhs.rawValue
}

Then

let planets: [Planets] = [.Mars, .Jupiter, .Earth]
let maxPlanet = maxElement(planets) // .Jupiter