> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sezzle.com/llms.txt
> Use this file to discover all available pages before exploring further.

# iOS SDK

This guide walks you through integrating the Sezzle iOS SDK into your app. By the end, your app will display Sezzle promotional messaging on product pages and launch Sezzle checkout.

### Prerequisites

* iOS 15.0+ deployment target
* Swift 5.9+
* A Sezzle merchant account with your <a href="https://dashboard.sezzle.com/merchant/settings/apikeys" target="_blank">Public API Key</a>
* A backend server to capture payments after checkout

<Tip>
  A working example app is included in the SDK repo at <a href="https://github.com/sezzle/sezzle-merchant-sdk-ios/tree/main/Example" target="_blank">Example/SezzleCheckoutExample</a>. It demonstrates all widget variants and both checkout modes.
</Tip>

## 1. Installation

<Tabs>
  <Tab title="Swift Package Manager">
    1. In Xcode, go to **File > Add Package Dependencies**
    2. Enter the repository URL:

    ```
    https://github.com/sezzle/sezzle-merchant-sdk-ios.git
    ```

    3. Select **Up to Next Major Version** from the latest release
    4. Add `SezzleMerchantSDK` to your target
  </Tab>

  <Tab title="CocoaPods">
    Add to your `Podfile`:

    ```ruby theme={"system"}
    pod 'SezzleMerchantSDK'
    ```

    Then run:

    ```bash theme={"system"}
    pod install
    ```
  </Tab>
</Tabs>

**Requirements:** iOS 15.0+, Swift 5.9+

## 2. Configuration

Initialize the SDK once at app startup in your `AppDelegate`:

```swift theme={"system"}
import SezzleMerchantSDK

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        SezzleSDK.shared.configure(
            publicKey: "sz_pub_your_key_here",
            environment: .production  // use .sandbox for testing
        )
        return true
    }
}
```

| Parameter     | Type                | Default       | Description                                    |
| ------------- | ------------------- | ------------- | ---------------------------------------------- |
| `publicKey`   | `String`            | Required      | Your Sezzle public API key                     |
| `environment` | `SezzleEnvironment` | `.production` | `.sandbox` for testing, `.production` for live |

<Warning>
  Never include your **private** API key in the app. The SDK only uses the public key. Use your private key server-side to capture payments.
</Warning>

## 3. Promotional Messaging

Add a `SezzlePromotionalView` to your product page to display installment pricing:

```swift theme={"system"}
import SezzleMerchantSDK

let promoView = SezzlePromotionalView(
    amountInCents: 9999,  // $99.99
    presentingFrom: self   // UIViewController for modal presentation
)
view.addSubview(promoView)
```

The widget automatically shows the correct message based on the price and updates when you call:

```swift theme={"system"}
promoView.update(amountInCents: 14999)  // price changed to $149.99
```

<Frame caption="Promotional widgets at different price points">
  <img src="https://mintcdn.com/sezzle/klJ95KzsWuUWpHvl/images/docs/guides/mobile/ios-product-page-light.png?fit=max&auto=format&n=klJ95KzsWuUWpHvl&q=85&s=00fc0f3d1283f897c0dbf172c327e093" alt="iOS Widgets" width="1206" height="2622" data-path="images/docs/guides/mobile/ios-product-page-light.png" />
</Frame>

### All Parameters

```swift theme={"system"}
SezzlePromotionalView(
    amountInCents: Int,
    currency: String = "USD",
    style: SezzlePromotionalStyle = .light,
    widgetConfig: SezzleWidgetConfig = .default,
    presentingFrom viewController: UIViewController
)
```

| Parameter        | Type                     | Default    | Description                                      |
| ---------------- | ------------------------ | ---------- | ------------------------------------------------ |
| `amountInCents`  | `Int`                    | Required   | Product price in cents (e.g., 4999 = \$49.99)    |
| `currency`       | `String`                 | `"USD"`    | ISO 4217 currency code (e.g., `"USD"`, `"CAD"`)  |
| `style`          | `SezzlePromotionalStyle` | `.light`   | `.light` for light backgrounds, `.dark` for dark |
| `widgetConfig`   | `SezzleWidgetConfig`     | `.default` | Controls pricing thresholds and Pay-in-5         |
| `presentingFrom` | `UIViewController`       | Required   | View controller to present the info modal from   |

<Tip>
  The widget auto-detects dark mode and switches styles via `traitCollectionDidChange`. If you want to force a specific style, pass `.light` or `.dark` explicitly.
</Tip>

### Widget Configuration

All config parameters are **optional** — the widget works out of the box with sensible defaults:

| Parameter            | Default            | Description                                                                     |
| -------------------- | ------------------ | ------------------------------------------------------------------------------- |
| `minPriceInCents`    | `3500` (\$35)      | Minimum price to show the widget                                                |
| `maxPriceInCents`    | `250000` (\$2,500) | Maximum price for short-term (PI4/PI5)                                          |
| `enablePayIn5`       | `true`             | Show "5 payments" for prices at or above the PI5 threshold                      |
| `pi5MinPriceInCents` | `5000` (\$50)      | Price threshold for Pay-in-5                                                    |
| `longTermConfig`     | `nil` (disabled)   | Enable long-term monthly payments — set to a `SezzleLongTermConfig` to activate |

To customize, pass only the values you want to override:

```swift theme={"system"}
let config = SezzleWidgetConfig(
    longTermConfig: SezzleLongTermConfig(
        minPriceInCents: 25_000  // $250+ shows monthly payments
    )
)

let promoView = SezzlePromotionalView(
    amountInCents: 79900,
    widgetConfig: config,
    presentingFrom: self
)
```

### Custom Promotional Text

If you need full control over the UI, use `SezzlePromoDataHandler` to get a styled `NSAttributedString` with the Sezzle logo inline:

```swift theme={"system"}
SezzlePromoDataHandler.getMessage(amountInCents: 9999) { attributedString in
    myLabel.attributedText = attributedString
}
```

## 4. Checkout

### Build the Checkout Object

```swift theme={"system"}
let checkout = SezzleCheckout(
    customer: SezzleCustomer(
        email: "customer@example.com",
        firstName: "Jane",
        lastName: "Doe",
        phone: "+15551234567",
        billingAddress: SezzleAddress(
            street: "123 Main St",
            city: "Minneapolis",
            state: "MN",
            postalCode: "55401",
            countryCode: "US"
        )
    ),
    order: SezzleOrder(
        referenceId: "order-12345",
        description: "Wireless Earbuds",
        amount: SezzleAmount(amountInCents: 4599, currency: "USD"),
        items: [
            SezzleItem(
                name: "Wireless Earbuds",
                sku: "WE-001",
                quantity: 1,
                price: SezzleAmount(amountInCents: 3999, currency: "USD")
            )
        ],
        taxAmount: SezzleAmount(amountInCents: 350, currency: "USD"),
        shippingAmount: SezzleAmount(amountInCents: 250, currency: "USD")
    )
)
```

#### Customer Fields

| Field             | Required | Description                         |
| ----------------- | -------- | ----------------------------------- |
| `email`           | Yes      | Customer email address              |
| `firstName`       | No       | Customer first name                 |
| `lastName`        | No       | Customer last name                  |
| `phone`           | No       | Customer phone number               |
| `dob`             | No       | Date of birth (`"YYYY-MM-DD"`)      |
| `billingAddress`  | No       | Billing address (`SezzleAddress`)   |
| `shippingAddress` | No       | Shipping address (`SezzleAddress`)  |
| `tokenize`        | No       | Tokenize customer for future orders |

#### Order Fields

| Field                      | Required | Description                                                                                                                                                       |
| -------------------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `referenceId`              | Yes      | Your internal order/reference ID                                                                                                                                  |
| `description`              | No       | Order description                                                                                                                                                 |
| `amount`                   | Yes      | Total order amount in cents + currency                                                                                                                            |
| `intent`                   | No       | [`.auth`](/docs/api/core/sessions/postv2session#body-order-intent) (default, capture later from your backend) or `.capture` (auto-capture at checkout completion) |
| `items`                    | No       | Line item details                                                                                                                                                 |
| `discounts`                | No       | Discount line items (`[SezzleDiscount]`)                                                                                                                          |
| `taxAmount`                | No       | Tax amount breakdown                                                                                                                                              |
| `shippingAmount`           | No       | Shipping amount breakdown                                                                                                                                         |
| `metadata`                 | No       | Custom key-value pairs. The SDK automatically includes `_sdk_platform`, `_sdk_version`, `_device_model`, and `_os_version` — avoid using keys prefixed with `_`.  |
| `locale`                   | No       | Checkout locale (`.enUS`, `.enCA`, `.frCA`)                                                                                                                       |
| `checkoutFinancingOptions` | No       | Restrict to specific plans: `.fourPayBiweekly`, `.fourPayMonthly`, `.sixPayMonthly`. Optional — omit to let Sezzle show all eligible plans.                       |

#### Address Fields (`SezzleAddress`)

| Field         | Description                     |
| ------------- | ------------------------------- |
| `name`        | Full name                       |
| `street`      | Street address line 1           |
| `street2`     | Street address line 2           |
| `city`        | City                            |
| `state`       | State or province               |
| `postalCode`  | Postal/ZIP code                 |
| `countryCode` | ISO country code (e.g., `"US"`) |
| `phone`       | Phone number                    |

### Start Checkout

```swift theme={"system"}
SezzleSDK.shared.startCheckout(
    checkout,
    from: self,            // presenting UIViewController
    delegate: self,        // SezzleCheckoutDelegate
    mode: .systemBrowser   // or .webView
)
```

### Handle the Result

Conform to `SezzleCheckoutDelegate`:

```swift theme={"system"}
extension ProductViewController: SezzleCheckoutDelegate {

    func checkoutDidComplete(result: SezzleCheckoutResult) {
        // For this flow, `result.orderUUID` is populated.
        // (For the server-driven flow, see Section 8.)
        if let orderUUID = result.orderUUID {
            // Send orderUUID to your backend to capture payment
            // POST /v2/order/{orderUUID}/capture
            print("Order completed: \(orderUUID)")
        }
    }

    func checkoutDidCancel() {
        // Customer closed checkout without completing
        print("Checkout cancelled")
    }

    func checkoutDidFail(error: SezzleError) {
        // Handle the error
        switch error {
        case .networkError(let underlying):
            print("Network error: \(underlying)")
        case .apiError(let statusCode, let message):
            print("API error \(statusCode): \(message)")
        case .browserDismissed:
            print("Browser dismissed")
        case .notConfigured:
            print("SDK not configured")
        case .invalidResponse:
            print("Invalid response")
        }
    }
}
```

<Note>
  After `checkoutDidComplete`, send `result.orderUUID` to your backend server. Your server should call `POST /v2/order/{orderUUID}/capture` using your **private** API key to capture the payment. See the [Orders API](/docs/api/core/orders/postv2capturebyorder) for details.
</Note>

## 5. WebView Mode

By default, checkout opens in `ASWebAuthenticationSession` (system browser). To keep the user inside your app, use WebView mode:

```swift theme={"system"}
SezzleSDK.shared.startCheckout(
    checkout,
    from: self,
    delegate: self,
    mode: .webView
)
```

<Tabs>
  <Tab title="System Browser (Default)">
    <Frame>
      <img src="https://mintcdn.com/sezzle/klJ95KzsWuUWpHvl/images/docs/guides/mobile/ios-system-browser-checkout.png?fit=max&auto=format&n=klJ95KzsWuUWpHvl&q=85&s=afe3f023e26e05c3ac879c3ef4bbd009" alt="System Browser" width="1206" height="2622" data-path="images/docs/guides/mobile/ios-system-browser-checkout.png" />
    </Frame>
  </Tab>

  <Tab title="WebView">
    <Frame>
      <img src="https://mintcdn.com/sezzle/klJ95KzsWuUWpHvl/images/docs/guides/mobile/ios-webview-checkout.png?fit=max&auto=format&n=klJ95KzsWuUWpHvl&q=85&s=4a5606d37ee85f0616ced7ba1ff440a8" alt="WebView" width="1206" height="2622" data-path="images/docs/guides/mobile/ios-webview-checkout.png" />
    </Frame>
  </Tab>
</Tabs>

| Mode             | Pros                                       | Cons                                       |
| ---------------- | ------------------------------------------ | ------------------------------------------ |
| `.systemBrowser` | Secure, shares Safari cookies, recommended | Brief context switch                       |
| `.webView`       | Stays in-app                               | No cookie sharing, user logs in every time |

## 6. Dark Mode

The SDK automatically adapts to the device's appearance setting. The promotional widget, installment modal, and checkout modal all support dark mode.

<Tabs>
  <Tab title="Light">
    <Frame>
      <img src="https://mintcdn.com/sezzle/klJ95KzsWuUWpHvl/images/docs/guides/mobile/ios-product-page-light.png?fit=max&auto=format&n=klJ95KzsWuUWpHvl&q=85&s=00fc0f3d1283f897c0dbf172c327e093" alt="Light Mode" width="1206" height="2622" data-path="images/docs/guides/mobile/ios-product-page-light.png" />
    </Frame>
  </Tab>

  <Tab title="Dark">
    <Frame>
      <img src="https://mintcdn.com/sezzle/klJ95KzsWuUWpHvl/images/docs/guides/mobile/ios-product-page-dark.png?fit=max&auto=format&n=klJ95KzsWuUWpHvl&q=85&s=ad32c685164f0e32c29528a325bbf47e" alt="Dark Mode" width="1206" height="2622" data-path="images/docs/guides/mobile/ios-product-page-dark.png" />
    </Frame>
  </Tab>
</Tabs>

If you need to force a specific style (e.g., your app doesn't follow the system setting):

```swift theme={"system"}
let promoView = SezzlePromotionalView(
    amountInCents: 9999,
    style: .dark,  // force dark style
    presentingFrom: self
)
```

## 7. Error Handling

All errors are delivered via `SezzleCheckoutDelegate.checkoutDidFail(error:)`:

| Error                            | When                                          | Suggested Action                    |
| -------------------------------- | --------------------------------------------- | ----------------------------------- |
| `.notConfigured`                 | `SezzleSDK.shared.configure()` was not called | Call `configure()` in `AppDelegate` |
| `.networkError`                  | No internet, timeout, DNS failure             | Show retry option                   |
| `.apiError(statusCode, message)` | Sezzle API returned an error                  | Check status code and message       |
| `.browserDismissed`              | User closed the browser/WebView               | Return to product page              |
| `.invalidResponse`               | Unexpected response format                    | Contact Sezzle support              |

## 8. Server-Driven Integration

For larger merchants who prefer a fully server-driven integration — no public key on-device, with the backend owning session creation, capture, and refunds — use the alternative `startCheckout` overload introduced in `1.2.0`.

### How it works

Your backend creates the checkout session via [`POST /v2/session`](/docs/api/core/sessions/postv2session) with merchant-chosen callback URLs, then hands `order.checkout_url` plus those URLs to the app. The SDK opens the URL, intercepts navigation to your callback URLs, and reports back via `SezzleCheckoutDelegate.checkoutDidComplete(result:)` with the full callback URL — so you can encode your own state in the query string and recover it on completion.

```mermaid theme={"system"}
sequenceDiagram
    participant App as Merchant App
    participant Backend as Merchant Backend
    participant SDK as Sezzle SDK
    participant API as Sezzle API

    App->>Backend: 1. Request checkout
    Backend->>API: 2. POST /v2/session (with merchant callback URLs)
    API-->>Backend: order.uuid + order.checkout_url
    Backend-->>App: 3. checkout_url + callback URLs
    App->>SDK: 4. startCheckout(checkoutURL:completeURL:cancelURL:…)
    SDK-->>App: 5. checkoutDidComplete(result.callbackURL)
    App->>Backend: 6. Map callback URL state → orderUUID
    Backend->>API: 7. Capture payment
```

### Step 1 — Backend creates the session

Pick any callback URLs you want — a custom scheme like `yourapp-sezzle://...` or HTTPS deep links. You can encode state in the query string (e.g. `yourapp-sezzle://done?orderRef=12345`) and recover it from the SDK callback.

Persist `order.uuid` server-side; the app only needs `order.checkout_url` plus the two callback URLs.

<Warning>
  **Don't put PII, auth tokens, or anything sensitive in the callback URL query string.** The callback URL is rendered in the browser and may be logged. Use opaque references (a random `orderRef` mapped server-side) — never the customer's email, phone, payment data, or session tokens.

  Custom URL schemes are also **not exclusive** — another app installed on the device can register the same scheme and intercept the callback. For maximum security in production, use **Universal Links** (verified HTTPS deep links) with `.webView` mode — they're tied to a domain you control, so other apps can't claim them.
</Warning>

### Step 2 — App presents checkout

```swift theme={"system"}
SezzleSDK.shared.startCheckout(
    checkoutURL: URL(string: checkoutURL)!,                              // from order.checkout_url (String → URL)
    completeURL: URL(string: "yourapp-sezzle://checkout/done")!,         // matches your server's complete_url.href
    cancelURL:   URL(string: "yourapp-sezzle://checkout/cancelled")!,    // matches your server's cancel_url.href
    from: self,
    delegate: self,
    mode: .webView   // or .systemBrowser
)
```

`SezzleSDK.shared.configure(publicKey:)` is **not** required for this flow — there's nothing for the SDK to authenticate.

### Step 3 — Read the result

```swift theme={"system"}
func checkoutDidComplete(result: SezzleCheckoutResult) {
    guard let callbackURL = result.callbackURL else { return }
    let orderRef = URLComponents(url: callbackURL, resolvingAgainstBaseURL: false)?
        .queryItems?
        .first(where: { $0.name == "orderRef" })?
        .value
    // Look up orderRef in your backend, then call /v2/order/{order.uuid}/capture
}
```

### Notes

* **`ASWebAuthenticationSession` requires a custom URL scheme** for the callback (`callbackURLScheme:` parameter). HTTPS callbacks aren't accepted by the auth session API. For HTTPS-based deep links (e.g. backed by Universal Links), use `.webView` mode — it intercepts navigation directly via `WKNavigationDelegate` and works with any scheme.
* **Match your URLs.** Whatever your backend passed as `complete_url.href` / `cancel_url.href`, pass the same URLs to `startCheckout`. The SDK matches on scheme + host + path; query params on the inbound URL are read by you.
* **`order.uuid` lives on your server.** It's not in the `checkout_url` and isn't echoed back — your backend already has it from the session-creation response.

## 9. Testing

Use the sandbox environment for testing:

```swift theme={"system"}
SezzleSDK.shared.configure(
    publicKey: "sz_pub_your_sandbox_key",
    environment: .sandbox
)
```

Use the [test data](/docs/api/test-cards) to complete test checkouts in sandbox.

<Warning>
  Switch to `.production` and your live public key before releasing to the App Store.
</Warning>