TerminalAPIKit for iOS helps with integrating Adyen's Terminal API into your iOS POS app. The kit provides the models to create a Terminal API SaletoPOIRequest, and to decode the received SaletoPOIResponse. For local Terminal API integrations, the kit also helps with protecting local communications.

This package is intended to be used in the following scenarios:

• when integrating POS Mobile SDK.
• when integrating client-side with an Adyen terminal using local Terminal API.
• when integrating server-side with an Adyen terminal using cloud Terminal API.

TerminalAPIKit for iOS is available through Swift Package Manager.

To install the kit:

1. In your Xcode project, go to File > Swift Packages > Add Package Dependency.
2. Enter https://github.com/Adyen/adyen-terminal-api-ios as the repository URL.
3. Specify the version to be at least 1.0.0.

For detailed instructions see Adding Package Dependencies to Your App.

The next sections describe how to create a request and how to decode the response.

To create a Terminal API SaleToPOIRequest for making a payment:

1. Create an instance of MessageHeader, representing the MessageHeader of your Terminal API request.

       let header = MessageHeader(
           protocolVersion: "3.0",
           messageClass: .service,
           messageCategory: .payment,
           messageType: .request,
           serviceIdentifier: "YOUR_SERVICE_IDENTIFIER",
           saleIdentifier: "YOUR_SERVICE_IDENTIFIER",
           poiIdentifier: "YOUR_POI_IDENTIFIER"
       )

2. Create an instance of PaymentTransaction, representing the body of your Terminal API PaymentRequest

       let saleData = SaleData(
           saleTransactionIdentifier:
               TransactionIdentifier(
                   transactionIdentifier: "YOUR_TRANSACTION_IDENTIFIER",
                   date: Date()
               )
       )
       
       let paymentTransaction = PaymentTransaction(
           amounts: Amounts(
               currency: "TRANSACTION_CURRENCY",
               requestedAmount: TRANSACTION_AMOUNT
           )
       )
       
       let paymentRequest = PaymentRequest(
           saleData: saleData,
           paymentTransaction: paymentTransaction
       )

3. Combine header and paymentRequest into an instance of Message<PaymentRequest>, representing the SaleToPOIRequest to send.

       let message = Message(header: header, body: paymentRequest)

4. Encode the message to JSON. TerminalAPIKit provides a Coder class to help with the JSON encoding and decoding.

       let jsonData = try Coder.encode(message)

5. Send the JSON message to the appropriate endpoint.

You'll receive a Terminal API response in JSON format from the endpoint that you sent your request to.

To handle the response:

1. Decode from Data as follows:

       let message = try Coder.decode(Message<PaymentResponse>.self, from: response)

2. After decoding, note the following:
   • The message object has a type of Message<PaymentResponse>, representing the Terminal API SaleToPOIResponse.
   • The header and body properties of the message represent the MessageHeader and PaymentResponse body.

If your integration uses local communications, you need to protect your integration against man-in-the-middle attacks, eavesdropping, and tampering. To protect communications, you need to:

• Validate the certificate of the payment terminal, to confirm your POS app is communicating directly with an Adyen-supplied terminal.
• Encrypt communications. This prevents intruders from reading the messages transmitted between the POS app and the terminal.

To help you with this, TerminalAPIKit provides helper functions to:

• Derive the encryption key from the shared key set up in your Adyen Customer Area.
• Encrypt and decrypt the messages passed between your terminal and your iOS or macOS POS application.

To derive the key used for encrypting and decrypting local communications between the terminal and your POS app:

1. Get the identifier, passphrase, and version of the shared key:
   In the Adyen Customer Area, under Point of sale, go to the terminal settings for your merchant account or store. Select Integrations and under Terminal API go to Encryption key. To see the key identifier, passphrase, and version values, select Decrypted.

2. Derive the key, making sure to pass the values in string form exactly as they appear in the Customer Area.

   let encryptionKey = try EncryptionKey(
       identifier: "KEY_IDENTIFIER",
       passphrase: "KEY_PASSPHRASE",
       version: KEY_VERSION
   )

Once the key is derived, you are ready to encrypt your local communications.

1. Create your request as described above. For example, create a Message<PaymentRequest>.
2. Encrypt your request.

   let encryptionKey: EncryptionKey = // the key you derived earlier
   let request: Message<PaymentRequest> = // the payment request you created
   let encryptedMessage: EncryptedMessage = try request.encrypt(using: encryptionKey)
   let json: Data = try Coder.encode(encryptedMessage)

3. Send the json to the terminal.
4. When you receive the response from the terminal, decrypt the response.

   let key: EncryptionKey = // the key you derived earlier
   let response: Data = // the response you receive from the terminal
   let encryptedMessage: EncryptedMessage = try Coder.decode(EncryptedMessage.self, from: response)
   let decryptedMessage: Message<PaymentResponse> = try decrypt(PaymentResponse.self, using: key)

To use TerminalAPIKit for iOS, you need:

• iOS 12.0 or later
• Xcode 13.4 or later
• Swift 5.6

If you have a feature request, or spotted a bug or a technical problem, create a GitHub issue. For other questions, contact our support team.

We strongly encourage you to join us in contributing to this repository so everyone can benefit from:

• New features and functionality
• Resolved bug fixes and issues
• Any general improvements

Read our contribution guidelines to find out how.

This repository is open source and available under the MIT license. For more information, see the LICENSE file.