Collect card payments while offline

To use offline mode, your application needs to consume version 3.3.0 or later of the Terminal iOS SDK.

Use a Configuration object to enable offline mode for the supported devices at your Location.

curl https://api.stripe.com/v1/terminal/configurations \
  -u "
sk_test_BQokikJOvBiI2HlWgH4olfQ2
:" \
  -d "offline[enabled]"=true

After you enable offline mode on a Configuration object, you can assign it to a Location. You can also enable offline mode by default for all Locations by updating the default Configuration object for your account. Configuration API changes can take several minutes to propagate to your SDK and reader, and require you to disconnect from and reconnect to your reader to take effect.

The SDK stores necessary Location information locally after connecting online. On subsequent offline connections, it uses the stored configuration information from that Location.

To collect payments with a smart reader while offline, you must have previously connected to any mobile reader of the same type at the same Location while online within the last 30 days, and have updated your reader’s software within that time.

If you attempt to connect to a reader while offline without meeting these requirements, the request fails with an error.

If you reinstall the application or perform any operation that clears the disk storage for the SDK (such as clearing your POS app’s cache in the POS device’s settings) you lose any payments that the SDK has stored and not yet forwarded. Make sure there are no stored payments before you perform any destructive action.

To allow your application to receive updates about the SDK’s network status and the state of forwarded payments, implement the OfflineDelegate protocol and pass it to the Terminal SDK. You must set OfflineDelegate before collecting payments offline.

import StripeTerminal

class CustomOfflineDelegate: OfflineDelegate {

    func terminal(_ terminal: Terminal, didChangeOfflineStatus offlineStatus: OfflineStatus) {
        // Check the value of `offlineStatus` and update your UI accordingly. For instance,
        // you can check the SDK's network status at `offlineStatus.sdk.networkStatus`.
        //
        // You can also check the SDK's current offline status using
        // `Terminal.shared.offlineStatus.sdk.networkStatus`.
    }

    func terminal(_ terminal: Terminal, didForwardPaymentIntent intent: PaymentIntent, error: Error?) {
        // The PaymentIntent was successfully forwarded, or an error occurred.
        // Reconcile any local state using the backend-generated `PaymentIntent.stripeId`
        // and the metadata you supplied when creating the PaymentIntent.
        //
        // Note that the `PaymentIntent.stripeId` may still be nil if creating the
        // PaymentIntent in the backend failed.
    }

    func terminal(_ terminal: Terminal, didReportForwardingError error: Error) {
        // A non-specific error occurred while forwarding a PaymentIntent.
        // Check the error message and your integration implementation to
        // troubleshoot.
    }
}

import UIKit
import StripeTerminal

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
        Terminal.setTokenProvider(APIClient.shared)
        Terminal.shared.offlineDelegate = CustomOfflineDelegate()
        // ...
        return true
    }

    // ...

}

To support operating offline, use the SDK’s createPaymentIntent to create PaymentIntent objects. This allows the SDK to create PaymentIntents while offline and forward them to Stripe after you’ve re-established connectivity.

While operating offline, PaymentIntent objects have a null stripeId. We recommend adding a custom identifier to the PaymentIntent’s metadata to help reconcile PaymentIntent objects created offline in your database.

After the PaymentIntent has been successfully forwarded to Stripe in Step 7, use your custom identifier to reconcile it in the OfflineDelegate.didForwardPaymentIntent callback.

import UIKit
import StripeTerminal

class PaymentViewController: UIViewController {

    // Action for a "Checkout" button
    func checkoutAction() throws {
        // Populate the correct transaction amount from your application.
        let amount = UInt(10_00)

        // Build up parameters for creating a `PaymentIntent`
        let params = try PaymentIntentParametersBuilder(
            amount: amount,
            currency: "usd"
        )
        .setMetadata(["offlineId": UUID().uuidString])
        .build()

        Terminal.shared.createPaymentIntent(params) { createResult, createError in
            if let error = createError {
                // Handle errors in your application.
                print("createPaymentIntent failed: \(error)")
            } else if let paymentIntent = createResult {
                print("createPaymentIntent succeeded")
                // If the `PaymentIntent` was created offline, its `stripeId` field will be nil.
                if let onlineCreatedId = paymentIntent.stripeId {
                    print("created online");
                } else {
                    print("created offline")
                }
            }
        }
    }
}

The Terminal.createPaymentIntent accepts a CreateConfiguration parameter. By default, if you’re operating offline, the Terminal SDK stores all offline payments, then forwards them to Stripe’s backend when connectivity is restored.

To customize this behavior, you can pass in a CreateConfiguration object with an offlineBehavior attribute set to as REQUIRE_ONLINE, PREFER_ONLINE or FORCE_OFFLINE.

Managing risk

Setting offlineBehavior to REQUIRE_ONLINE fails the current transaction if you’re operating offline. For example, you might want to disallow transactions above a certain amount or disallow all offline transactions if the SDK has stored a set of transactions whose sum exceeds a certain amount.

The SDK exposes two properties to help you manage risk:

1. Terminal.offlineStatus.sdk.offlinePaymentsCount
2. Terminal.offlineStatus.sdk.offlinePaymentAmountsByCurrency

Managing latency while offline

Based on your network connectivity, the Terminal SDK automatically determines whether to collect payments online or offline. However, you might want to operate offline despite having an active network connection (for example, if you need to collect transactions quickly and your network connection is slow). You can pass a CreateConfiguration object with offlineBehavior set to FORCE_OFFLINE to collect the payment offline regardless of connectivity.

Payments collected offline while the Terminal SDK has an active network connection are forwarded in the background.

import UIKit
import StripeTerminal

class PaymentViewController: UIViewController {

    // Action for a "Checkout" button
    func checkoutAction() throws {
        // ...build up parameters and callback for creating a `PaymentIntent`

        // Your app might want to prevent offline payments for too large an amount.
        // Here, we block the payment if the amount is over 1000 usd.
        // Otherwise, we allow collecting offline if the network connection is unavailable.
        let offlineBehavior: SCPOfflineBehavior = {
            if amount > UInt(1_000_00) {
                return .requireOnline
            } else {
                return .preferOnline
            }
        }()

        let createConfiguration = try CreateConfigurationBuilder().setOfflineBehavior(offlineBehavior).build()
        Terminal.shared.createPaymentIntent(params, createConfig: createConfiguration) { createResult, createError in
            // handle success or failure
        }
    }
}

Collecting payments while offline is similar to collecting payments while online. Use the didRequestReaderInput method to display the valid card presentment options to the customer.

import UIKit
import StripeTerminal

class PaymentViewController: UIViewController {

    // Action for a "Checkout" button
    func checkoutAction() {
        Terminal.shared.collectPaymentMethod(paymentIntent) { collectResult, collectError in
            if let error = collectError {
                print("collectPaymentMethod failed: \(error)")
            }
            else if let paymentIntent = collectResult {
                print("collectPaymentMethod succeeded")
                // ... Confirm the payment
            }
        }
    }
}

Confirming payments while offline is similar to confirming payments while online. The primary difference is that your integration must handle offline-specific error cases, such as when the transaction exceeds the Stripe-enforced offline maximum of 10,000 USD or equivalent in your operating currency.

In some cases, the SDK might create a PaymentIntent online, but confirm it while offline. When this happens, the PaymentIntent might have a non-null stripeId. If it was confirmed offline, offlineDetails will be defined and populated.

import UIKit
import StripeTerminal

class PaymentViewController: UIViewController {

    // Action for a "Checkout" button
    func checkoutAction() {

        Terminal.shared.confirmPaymentIntent(paymentIntent) { confirmResult, confirmError in
            if let error = confirmError {
                // Handle offline-specific errors in your application (for example,
                // unsupported payment method).
                print("confirmPaymentIntent failed: \(error)")
            } else if let confirmedPaymentIntent= confirmResult {
                print("confirmPaymentIntent succeeded")
                if let offlineDetails = paymentIntent.offlineDetails {
                    print("confirmed offline");
                } else {
                    print("confirmed online")
                }
            }
        }
    }
}

Providing receipts

You might require information about the card used to complete a payment while offline. For example, you might need to generate a receipt for customers who require one at the time of purchase.

If the PaymentIntent is confirmed offline, retrieve its OfflineCardPresentDetails from the paymentIntent.offlineDetails.offlineCardPresentDetails property.

This hash contains a ReceiptDetails property you can use to generate a receipt, as well as other card details like the cardholder name and card brand.

The account_type and authorization_response_code receipt fields are unavailable on PaymentIntents processed offline. Prebuilt email receipts are only sent after connectivity is restored and the payment is successfully captured.

When Internet access is restored, the SDK automatically begins forwarding the stored offline payments.

The SDK attempts to forward payments even if its network status is offline. This means your connection token provider might receive a request to provide a connection token even when the device is offline.

If you power off your POS device too soon, your payments might not be forwarded. You can query Terminal.offlineStatus.sdk.networkStatus to make sure your POS is online and can forward payments, and Terminal.offlineStatus.sdk.offlinePaymentsCount to check how many payments the Terminal SDK has to be forwarded.

While offline, you can create PaymentIntents with captureMethod set to automatic.

After you confirm these PaymentIntents, they have a Succeeded status instead of RequiresCapture. Stripe automatically captures the payments after you forward them.

If you opt for manual capture, payments that are successfully forwarded and authorized require capture from your backend or application.

• To capture payments from your backend, use webhooks to listen for PaymentIntents with a requires_capture status.
• To capture payments from your application, wait for your application to receive calls to OfflineDelegate.didForwardPayment for each PaymentIntent as the SDK forwards it. A PaymentIntent is ready to capture if its status is RequiresCapture and the offlineDetails is null or has a requiresUpload value of NO .

Terminal.shared.confirmPaymentIntent(paymentIntent) { confirmResult, confirmError in
    if let error = confirmError {
        // Handle offline-specific errors in your application (for example,
        // unsupported payment method).
        print("confirmPaymentIntent failed: \(error)")
    } else if let confirmedPaymentIntent = confirmResult {
        if intent.status == .requiresCapture {
            if let offlineDetails = confirmedPaymentIntent.offlineDetails(),
               offlineDetails.requiresUpload {
                // Offline payment, wait for `didForwardPaymentIntent` (see snippet below)
            } else {
                // Online payment, can be captured now
            }
        }
        // else, handle other intent.status results here
    }
}

Capture an offline payment after the SDK forwards it in your OfflineDelegate’s didForwardPaymentIntent:

import StripeTerminal

class CustomOfflineDelegate: OfflineDelegate {
    // ...
    func terminal(_ terminal: Terminal, didForwardPaymentIntent intent: PaymentIntent, error: Error?) {
        if let error = error {
            // Handle the error appropriate for your application
            return
        }

        if intent.status == .requiresCapture {
            // The intent is ready to be captured.
        } else {
            // Handle the intent.status as appropriate.
        }
    }
    // ...
}

After authorization, you can use the PaymentIntents API to examine offline details on a payment. Access the payment method details on the latest Charge object on a PaymentIntent to determine if it was collected offline.