Solve New Enum Cases. (Note: Required Swift 5.3, Refer: https://github.com/apple/swift-evolution/blob/master/proposals/0280-enum-cases-as-protocol-witnesses.md)

UnknownEnumCase.swift

protocol UnknownCase: RawRepresentable, CaseIterable where RawValue: Equatable & Codable {
    static var unknownCase: Self { get }
}

extension UnknownCase {
    init(rawValue: RawValue) {
        let value = Self.allCases.first { $0.rawValue == rawValue }
        self = value ?? Self.unknownCase
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        let rawValue = try container.decode(RawValue.self)
        let value = Self(rawValue: rawValue)
        self = value ?? Self.unknownCase
    }
}

//
// Usage
//
enum YourCodableEnum: Int, Codable, UnknownCase {   // Conform to 'UnknownCase' protocol
    case unknownCase    // Add this case
    case profile = 2, event = 6
}