NotAGreatFilter.swift

enum FilterValue {
    case string(String)
    case bool(Bool)

    func matches(value: Any) -> Bool {
        switch self {
        case .string(let stringValue):
            return (value as? String) == stringValue
        case .bool(let boolValue):
            return (value as? Bool) == boolValue
        }
    }
}

enum FilterQuery {
    case none
    case filters([String: FilterValue]) //[Key: FilterValue]
}