Is there a better way to do this?

enumFilter.swift

enum Thing {
    case empty
    case int(Int)
}

let things: [Thing] = [.empty, .int(3), .int(7)]

// Surely there's a more concise way to write this `filter` closure?
let intThings = things.filter({
    if case Thing.int = $0 { return true }
    else { return false }
})

Things that don't work:

things.filter({ case Thing.int = $0 })
things.filter({ $0 is Thing.int })

Not a pretty solution but I’ve done the following before. It tidied up the call site and could arguably be generated

enum Thing {
    case empty
    case int(Int)

    var unassociated: Unassociated {
        switch self {
        case .empty: return .empty
        case int: return .int
        }
    }

    enum Unassociated {
        case empty
        case int
    }
}

It then becomes at the call site

things.filter { $0.unassociated == .int }