Swift

Allow your iOS users to buy stablecoins with credit cards and Apple Pay

In this guide, you’ll learn how to:

• Install the Swift SDK
• Create an Onramp order for your authenticated users
• Use the embedded checkout component to handle KYC, payment, and delivery

Native iOS onramp with Apple Pay support

Before you start

Set up your project and get an API key.

Swift SDK on GitHub

View the open source Swift Checkout SDK repository.

Staging is self-serve — start testing with a staging console account. Production access requires a signed Order Form and completed KYB verification. Contact sales to get started.

Prerequisites

• iOS 14.0+
• SwiftUI framework
• Xcode 13.0 or later

Install the Crossmint Swift SDK using Swift Package Manager.

In Xcode, go to File > Add Package Dependencies and add:

https://github.com/Crossmint/crossmint-checkout-swift

Select the CrossmintCheckout product for your target.

• Create a server-side API key with the orders.create and orders.read scopes enabled. In staging, all scopes are included in your API key.

Add Onramp to Your App

1. Create the order

   If you want to enable onramp orders to external wallets (EOAs or third-party smart wallets) instead of Crossmint wallets, see the Onramp to External Wallets guide before proceeding.

   Use the Create Order API to initiate the purchase process from your backend.

   Use the following token addresses for USDC on staging:

   Chain	Staging Token Address
   Solana Devnet	4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU
   Base Sepolia	0x036CbD53842c5426634e7929541eC2318f3dCF7e
   Stellar Testnet	CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA

   🚨 IMPORTANT: The payment.receiptEmail parameter is required for compliance reasons. Crossmint uses this email to determine whether KYC is required for the order.

   Example API call for USDC on Solana Devnet:

   curl --request POST \
     --url https://staging.crossmint.com/api/2022-06-09/orders \
     --header 'Content-Type: application/json' \
     --header 'x-api-key: <YOUR_SERVER_API_KEY>' \
     --data '{
       "lineItems": [
         {
           "tokenLocator": "solana:4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU",
           "executionParameters": {
             "mode": "exact-in",
             "amount": "5"
           }
         }
       ],
       "payment": {
         "method": "card",
         "receiptEmail": "[e-mail]"
       },
       "recipient": {
         "walletAddress": "example-wallet-address"
       }
     }'
   

   Example Response

   {
     "clientSecret": "example-client-secret",
     "order": {
       "orderId": "example-order-id",
       "phase": "payment",
       "locale": "en-US",
       "lineItems": [
         {
           "chain": "solana",
           "metadata": {
             "name": "USDC",
             "description": "USDC Token",
             "imageUrl": "https://cryptologos.cc/logos/usd-coin-usdc-logo.svg?v=040"
           },
           "quote": {
             "status": "valid",
             "charges": {
               "unit": {
                 "amount": "1.47",
                 "currency": "usd"
               }
             },
             "totalPrice": {
               "amount": "2",
               "currency": "usd"
             },
             "quantityRange": {
               "lowerBound": "1.36",
               "upperBound": "1.36"
             }
           },
           "delivery": {
             "status": "awaiting-payment",
             "recipient": {
               "locator": "solana:example-wallet-address",
               "walletAddress": "example-wallet-address"
             }
           },
           "executionMode": "exact-in",
           "maxSlippageBps": "0",
           "executionParams": {
             "mintHash": "example-mint-hash",
             "mode": "exact-in",
             "amount": "2"
           }
         }
       ],
       "quote": {
         "status": "valid",
         "quotedAt": "2025-03-07T23:04:11.996Z",
         "expiresAt": "2025-03-07T23:14:11.996Z",
         "totalPrice": {
           "amount": "2",
           "currency": "usd"
         }
       },
       "payment": {
         "method": "basis-theory",
         "currency": "usd",
         "status": "requires-kyc",
         "preparation": {
           "kyc": {
             "provider": "persona",
             "templateId": "example-template-id",
             "referenceId": "example-reference-id"
           }
         }
       }
     }
   }
   
2. Use the checkout component

   Once you have the order response with orderId and clientSecret, use Crossmint’s embedded checkout component in your SwiftUI view.

   The component supports native Apple Pay for a seamless iOS payment experience.

   import SwiftUI
   import CrossmintCheckout
   
   struct ContentView: View {
       var body: some View {
           CrossmintEmbeddedCheckout(
               orderId: <your_order_id>,
               clientSecret: <your_client_secret>,
               payment: CheckoutPayment(
                   crypto: CheckoutCryptoPayment(enabled: false),
                   fiat: CheckoutFiatPayment(
                       enabled: true,
                       allowedMethods: CheckoutAllowedMethods(
                           googlePay: false,
                           applePay: true,  // Native Apple Pay support
                           card: true
                       )
                   )
               ),
               appearance: CheckoutAppearance(
                   rules: CheckoutAppearanceRules(
                       destinationInput: CheckoutDestinationInputRule(display: "hidden"),
                       receiptEmailInput: CheckoutReceiptEmailInputRule(display: "hidden")
                   )
               )
           )
       }
   }
   

   Key features:

   • Native Apple Pay: Smooth integration with iOS payment system
   • SwiftUI Components: Modern declarative UI framework
   • Automatic KYC: Handles verification flow automatically
   • Customizable Appearance: Control visibility of UI elements
3. Track the order

   After the user completes payment, you can track the order status using webhooks or polling.

   Webhooks (Recommended)

   Configure a webhook endpoint to receive real-time order status updates:

   1. Go to the Crossmint Console
   2. Add your webhook endpoint URL
   3. Subscribe to orders.delivery.completed and orders.delivery.failed events to track the final order outcome. You can also subscribe to orders.payment.succeeded for an intermediate payment confirmation.

   Example webhook payload:

   {
     "actionId": "example-order-id",
     "type": "orders.delivery.completed",
     "data": {
       "orderId": "example-order-id",
       "phase": "completed",
       "payment": {
         "status": "completed",
         "method": "card",
         "currency": "usd"
       },
       "lineItems": [
         {
           "delivery": {
             "status": "completed"
           }
         }
       ]
     }
   }
   

   For detailed setup instructions, see the Webhooks documentation.

   Polling

   Poll the order status endpoint from your backend:

   curl --request GET \
     --url https://staging.crossmint.com/api/2022-06-09/orders/{orderId} \
     --header 'x-api-key: YOUR_SERVER_API_KEY'
   

   Check the order.payment.status and order.lineItems[].delivery.status fields to track progress.

Transaction Completion

Upon successful payment:

1. KYC Verification

   The embedded checkout component handles all the complexity of KYC verification automatically.

2. Token Delivery

   The purchased tokens (minus fees) are sent directly to the user's wallet.

3. Receipt Sent

   User receives an email receipt from [e-mail].

Next Steps

• Explore the Payment Methods Guide to learn about different payment options
• See the Production Launch Guide for going live

• View the Swift Checkout SDK source code on GitHub