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Reputation: 2513

How can I check an enum's value and its associated enum's value with a single case statement?

Please have a look at the switch statement below. I am looking for a more swifty way to perform the test; something like:

case let .b(other) where .x = other // This does not compile

Is it possible?

enum MyEnum {
    case a
    case b(MyOtherEnum)
}

enum MyOtherEnum {
    case x
    case y
}

func check(value: MyEnum) {
    switch value {
    case let .b(other):
        if case .x = other {
            print("Got it!")
        }
    default:
        break
    }
}

Upvotes: 2

Views: 395

Answers (3)

Martin R
Martin R

Reputation: 539685

If you are only interested in the case MyEnum.b(.x) and no other cases then you can also use if with a case pattern:

func check(value: MyEnum) {
    if case .b(.x) = value {
        print("Got it!")
    }
}

Upvotes: 2

Scott Thompson
Scott Thompson

Reputation: 23701

func check(value: MyEnum) {
    switch value {
    case .b(.x):
        print("Got it!")
    case .b(_):
        print("Not it!")
    default:
        break
    }
}

let myVar = MyEnum.b(.x)
check(value: myVar)
// prints "Got it!"

Upvotes: 1

nathangitter
nathangitter

Reputation: 9777

You need to use == not =:

case let .b(other) where .x == other

This works fine for me:

func check(value: MyEnum) {
    switch value {
    case let .b(other) where other == .x:
        print("bx")
    case let .b(other) where other == .y:
        print("by")
    default:
        break
    }
}

check(value: MyEnum.b(.x)) // prints "bx"
check(value: MyEnum.b(.y)) // prints "by"

Upvotes: 1

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