Swift

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

The Swift SDK is currently in Beta.

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 SDK repository.

You can start testing Onramp in staging. Once you are ready to go live, reach out to sales to enable the feature in production

Requirements

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

1. Installation

Install the Crossmint Swift SDK using Swift Package Manager.

1. Add Package Dependency

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

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

   Select the CrossmintCheckout product for your target.

2. Create API key

   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.

2. Create Order

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

🚨 IMPORTANT: The payment.receiptEmail parameter is required for compliance reasons. This email is used by Crossmint to determine whether KYC is required for the order. The API accepts either recipient.email OR recipient.walletAddress, not both.

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": "checkoutcom-flow",
      "currency": "usd",
      "status": "requires-kyc",
      "preparation": {
        "kyc": {
          "provider": "persona",
          "templateId": "example-template-id",
          "referenceId": "example-reference-id"
        }
      }
    }
  }
}

3. Use 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 Checkout

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

4. Track 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 order.payment.succeeded and order.delivery.succeeded events

Example webhook payload:

{
  "type": "order.payment.succeeded",
  "orderId": "example-order-id",
  "payment": {
    "status": "succeeded",
    "method": "card",
    "currency": "usd"
  }
}

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.

5. 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].

6. Next Steps

• Explore our Payment Methods Guide to learn about different payment options
• Check out our Production Launch Guide for going live

• View the Swift SDK source code on GitHub