Accept reader payments on iOS

Start a reader checkout after setting up the SDK, authenticating, and pairing a reader. For a minimal payment example, use the iOS quickstart.

The examples below are methods in your app’s UIViewController. They use the SDK directly and do not require sample-app controls. See the checkout reference for request properties, method signatures, and error codes.

Implement full checkout

1. Read the currency from the logged-in merchant. The checkout currency must match it.
2. Create a request with the amount to charge. Use NSDecimalNumber to represent the amount.
3. If isProcessAsRequired is true, ask the customer to choose credit or debit before starting checkout. For credit payments in those markets, also ask for the number of installments.
4. Start checkout and check the result in its completion handler. Save the transaction code when one is returned.

The examples accept the amount and the customer’s credit/debit selection as arguments. Use ProcessAs.notSet in Swift or SMPProcessAsNotSet in Objective-C when selection is not required. The installments argument is only used for credit payments.

private func requestCheckout(
    total: NSDecimalNumber,
    processAs: ProcessAs = .notSet,
    installments: Int = 1
) {
    guard let currencyCode = SumUpSDK.currentMerchant?.currencyCode else {
        print("Log in before starting a payment")
        return
    }
    guard !SumUpSDK.isProcessAsRequired || processAs != .notSet else {
        print("Ask the customer to choose credit or debit before starting checkout")
        return
    }

    let request = CheckoutRequest(total: total, title: nil, currencyCode: currencyCode)
    request.foreignTransactionID = UUID().uuidString
    request.processAs = processAs
    if processAs == .credit {
        request.numberOfInstallments = installments
    }

    SumUpSDK.checkout(with: request, from: self) { result, error in
        if let error {
            print("Checkout error: \(error.localizedDescription)")
            return
        }
        guard let result, result.success else {
            print("Payment did not succeed")
            return
        }
        print("Payment successful: \(result.transactionCode ?? "")")
    }
}

- (void)requestCheckoutWithTotal:(NSDecimalNumber *)total
                      processAs:(SMPProcessAs)processAs
                   installments:(NSInteger)installments {
    NSString *currencyCode = SMPSumUpSDK.currentMerchant.currencyCode;
    if (currencyCode.length == 0) {
        NSLog(@"Log in before starting a payment");
        return;
    }
    if (SMPSumUpSDK.isProcessAsRequired && processAs == SMPProcessAsNotSet) {
        NSLog(@"Ask the customer to choose credit or debit before starting checkout");
        return;
    }

    SMPCheckoutRequest *request = [SMPCheckoutRequest requestWithTotal:total
                                                              title:nil
                                                       currencyCode:currencyCode];
    request.foreignTransactionID = NSUUID.UUID.UUIDString;
    request.processAs = processAs;
    if (processAs == SMPProcessAsCredit) {
        request.numberOfInstallments = installments;
    }

    [SMPSumUpSDK checkoutWithRequest:request fromViewController:self
                         completion:^(SMPCheckoutResult *result, NSError *error) {
        if (error) {
            NSLog(@"Checkout error: %@", error.localizedDescription);
            return;
        }
        if (!result.success) {
            NSLog(@"Payment did not succeed");
            return;
        }
        NSLog(@"Payment successful: %@", result.transactionCode ?: @"");
    }];
}

Keep your order reference associated with foreignTransactionID. If a connection problem leaves the result uncertain, use the Transactions API to check the transaction before starting another payment. Pass the reference as the foreign_transaction_id query parameter.

Note on tipping

Choose one of these tipping options before starting checkout:

Credit/Debit selection (processAs property)

In some markets, a card can support both credit and debit. Your app must ask the customer which to use before starting checkout.

For countries that do not require credit/debit selection, you can set the processAs property of SMPCheckoutRequest to SMPProcessAsNotSet.

Check SMPSumUpSDK.isProcessAsRequired to find out whether the merchant’s country requires this choice.

If needed, your app should set the processAs property of SMPCheckoutRequest to SMPProcessAsCredit or SMPProcessAsDebit after showing its own UI that prompts the customer to select Credit or Debit.

SDK 6.0 and earlier presented two screens during the checkout that prompted the user to select Credit or Debit, and if Credit, to also choose the number of installments. This behavior was previously available via SMPProcessAsPromptUser.

Installments

When SMPProcessAsCredit is used, you should obtain the number of installments from the customer using your own UI. Assign the positive, non-zero value to numberOfInstallments on SMPCheckoutRequest.

Verify the payment

Check CheckoutResult.success before treating the order as paid, and save the transaction code when one is returned. Test success, declines, and interrupted connections with the in-person payment testing guide.

Next steps

• Read checkout properties and errors.
• Accept offline payments.