Swift Design Pattern: Swift Enum's, the Switch statement and an alternative solution

I love the Swift Enum's. Full stop.

But working with enum's and the switch statement? I don't like that too much, tends to make the code pretty obscure. In Swift 2 there is the if case which is better, but still does not make my code very readable.

Luckily there is an alternative solution possible, what I would call the is-enum pattern:

Traditionally I would define an enum like:

enum ValueItem {

    case NULL

    case BOOL(Bool)

    case STRING(String)

    case NUMBER(NSNumber)

    case ERROR(code: String, reason: String)

}

Let's say I am interested in a number and bool and only then want to execute some code. I have the following possibilities:

    // Only for bool and number:

    

    switch val {

    case .BOOL, .NUMBER:

        // code

    default: break

    }

Or:

    // Only for bool and number:

    

    var boolOrNum: false

    if case .NUMBER = val { boolOrNum = true }

    if case .BOOL = val { boolOrNum = true }

    

    if boolOrNum {

        // code

    }

Neither of which is not very transparent imo. What I would like is this:

    if val.isBool || val.isNumber {

        // code

    }

Even the comment line is no longer needed, the code is completely self documenting.

The only thing we have to do to enable this is to add the corresponding var's to the enum declaration:

enum ValueItem {

    case NULL

    case BOOL(Bool)

    case STRING(String)

    case NUMBER(NSNumber)

    case ERROR(code: String, reason: String)

    

    var isNull: Bool {

        if case .NULL = self { return true }

        return false

    }

    var isBool: Bool {

        if case .BOOL = self { return true }

        return false

    }

    

    var isString: Bool {

        if case .STRING = self { return true }

        return false

    }

    var isNumber: Bool {

        if case .NUMBER = self { return true }

        return false

    }

    var isError: Bool {

        if case .ERROR = self { return true }

        return false

    }

}

Easy.

Happy coding...

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