Алгоритм проверки типа ML-подобного сопоставления с образцом?

Я обновил версию Эрика для Swift 3:

class KeyChain {

    class func save(key: String, data: Data) -> OSStatus {
        let query = [
            kSecClass as String       : kSecClassGenericPassword as String,
            kSecAttrAccount as String : key,
            kSecValueData as String   : data ] as [String : Any]

        SecItemDelete(query as CFDictionary)

        return SecItemAdd(query as CFDictionary, nil)
    }

    class func load(key: String) -> Data? {
        let query = [
            kSecClass as String       : kSecClassGenericPassword,
            kSecAttrAccount as String : key,
            kSecReturnData as String  : kCFBooleanTrue,
            kSecMatchLimit as String  : kSecMatchLimitOne ] as [String : Any]

        var dataTypeRef: AnyObject? = nil

        let status: OSStatus = SecItemCopyMatching(query as CFDictionary, &dataTypeRef)

        if status == noErr {
            return dataTypeRef as! Data?
        } else {
            return nil
        }
    }

    class func createUniqueID() -> String {
        let uuid: CFUUID = CFUUIDCreate(nil)
        let cfStr: CFString = CFUUIDCreateString(nil, uuid)

        let swiftString: String = cfStr as String
        return swiftString
    }
}

extension Data {

    init<T>(from value: T) {
        var value = value
        self.init(buffer: UnsafeBufferPointer(start: &value, count: 1))
    }

    func to<T>(type: T.Type) -> T {
        return self.withUnsafeBytes { $0.pointee }
    }
}

Пример использования:

    let int: Int = 555
    let data = Data(from: int)
    let status = KeyChain.save(key: "MyNumber", data: data)
    print("status: ", status)

    if let receivedData = KeyChain.load(key: "MyNumber") {
        let result = receivedData.to(type: Int.self)
        print("result: ", result)
    }