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

# iOS Reference

Parameters, customizations, and advanced features for all Yuno iOS SDK flows. For integration setup, see [Payment flows (iOS)](/docs/sdks/full-checkout/ios-payments), [Enrollment flows (iOS)](/docs/sdks/card-enrollment/ios-enrollment), and [integration modes](/docs/sdks/overview/choose-integration).

## Key parameters (checkout session creation)

When creating a checkout session on your backend for payment flows, the following parameters are commonly used across iOS SDKs:

| Parameter            | Required | Description                                                                                                                                                                                                                                                                                                        |
| -------------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `amount`             | Yes      | The primary transaction amount object containing `currency` (ISO 4217 code) and `value` (numeric amount in that currency).                                                                                                                                                                                         |
| `alternative_amount` | No       | An alternative currency representation of the transaction amount with the same structure as `amount` (`currency` and `value`). Useful for multi-currency scenarios, such as displaying prices to customers in their preferred currency (e.g., USD) while processing the payment in the local currency (e.g., COP). |

## Payment parameters (full reference)

Parameters for payment flows. All parameters used in [Payment flows (iOS)](/docs/sdks/full-checkout/ios-payments) are listed here with full detail.

| Parameter                  | Type             | Required | Description                                                                                                                                                                                                                                                                                              |
| -------------------------- | ---------------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `checkoutSession`          | string           | Yes      | Checkout session ID from your backend (Create checkout session API). Required for all payment flows.                                                                                                                                                                                                     |
| `countryCode`              | string           | Yes      | ISO country code where the payment runs (e.g. `BR`, `US`). Determines available payment methods and compliance.                                                                                                                                                                                          |
| `language`                 | string           | No       | Language code for the SDK UI (e.g. `en`, `pt-BR`). Optional. See [Supported languages](/docs/sdks/resources/languages-supported) when available.                                                                                                                                                         |
| `viewController`           | UIViewController | Yes\*    | The view controller that presents the payment flow. The SDK uses it to present modals and capture result.                                                                                                                                                                                                |
| `yunoCreatePayment(with:)` | delegate         | Yes      | Delegate method: create the payment on your backend using the one-time token provided by the SDK. After creating the payment via the API, inform the SDK so it can continue the flow.                                                                                                                    |
| `yunoPaymentResult(_:)`    | delegate         | No       | Delegate method: invoked when the payment flow finishes. Receives a `Yuno.Result` enum value (`.succeeded`, `.fail`, `.processing`, `.reject`, `.userCancelled`, `.internalError`). These values map to [payment statuses](/reference/getting-started/response-codes). Use for UI updates or navigation. |

## YunoConfig options (initialize)

Runtime behavior and appearance are configured via `YunoConfig` when calling `Yuno.initialize(apiKey:config:)`. All parameters used across iOS payment and enrollment flows are listed below. For visual styling (fonts, colors, buttons), see [SDK customizations (iOS)](/docs/sdks/customization/ios).

| Parameter         | Type       | Required | Description                                                                                                                                                                                                                                               |
| ----------------- | ---------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `appearance`      | Appearance | No       | Custom appearance (fonts, colors, buttons). Use `Yuno.Appearance(...)` to set `fontFamily`, `accentColor`, `buttonBackgroundColor`, `buttonTitleColor`, and related fields. See [SDK customizations (iOS)](/docs/sdks/customization/ios) for all options. |
| `saveCardEnabled` | boolean    | No       | When `true`, allows the user to save or enroll the card during payment. Requires backend support for vaulting.                                                                                                                                            |

## Enrollment parameters (full reference)

Parameters for enrollment flows. All parameters used in [Enrollment flows (iOS)](/docs/sdks/card-enrollment/ios-enrollment) are listed here with full detail.

| Parameter                  | Type             | Required | Description                                                                                                                                                |
| -------------------------- | ---------------- | -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `customerSession`          | string           | Yes      | Customer session ID from Create customer session API. Required. Associates the enrolled payment method with a specific customer.                           |
| `countryCode`              | string           | Yes      | ISO country code (e.g. `BR`, `US`). Required for enrollment.                                                                                               |
| `language`                 | string           | No       | Language code for the SDK UI. Optional.                                                                                                                    |
| `viewController`           | UIViewController | Yes\*    | The view controller that presents the enrollment flow. Required for delegate-based enrollment.                                                             |
| `yunoEnrollmentResult(_:)` | delegate         | No       | Delegate method: invoked when enrollment finishes. Receives the result (e.g. vaulted token, status). Use for UI updates or navigation.                     |
| `YunoConfig`               | YunoConfig       | No       | Same options as payment (e.g. `appearance`, `saveCardEnabled`, `keepLoader`). See [YunoConfig options (initialize)](#yunoconfig-options-initialize) above. |

## Enrolling payment methods

You can enroll payment methods (store cards for future use) during the payment flow or via dedicated enrollment flows. For payment flows, enable save card in `YunoConfig` and set `payment_method.vault_on_success` (or equivalent) when creating the checkout session where supported. For dedicated enrollment, see [Enrollment flows (iOS)](/docs/sdks/card-enrollment/ios-enrollment).