Functions

SDK Initialization

The Checkout SDK is initialized using the CheckoutArguments class, which includes the properties listed below.

To initialize the SDK, an instance of CheckoutArguments must be passed as an argument to the OttuCheckoutWidget object.

For a detailed implementation example, refer to the Example section.

Properties

merchantId string required

It is used to define the Ottu merchant domain and must be set to the root domain of the Ottu account, excluding the https:// or http:// prefix.

For example, if the Ottu URL is https://example.ottu.com, the corresponding merchant_id is example.ottu.com.

This property is required to ensure that the checkout process is correctly linked to the associated Ottu merchant account.

apiKey string required

It is the Ottu API public key, used for authentication when communicating with Ottu's servers during the checkout process.

Ensure that only the public key is used. The private key must remain confidential and must never be shared with any clients.

sessionId string required

It is a unique identifier for the payment transaction associated with the checkout process.

This identifier is automatically generated when a payment transaction is created. For further details on how to use the session_id parameter in the Checkout API, refer to the session_id documentation.

formsOfPayment array optional

The formsOfPayment parameter is used to customize the forms of payment displayed in the checkout process. By default, all forms of payment are enabled.

Available options for formsOfPayment:

• applePay: The Apple Pay payment method is supported, allowing purchases to be made using Apple Pay-enabled devices.

• cardOnsite: A direct (onsite) payment method, where customers are required to enter their card details directly within the SDK.

• tokenPay: A method utilizing tokenization, ensuring that customer payment information is securely stored and processed.

• redirect: A payment method where customers are redirected to an external payment gateway or a third-party processor to complete the transaction.

• stcPay: A method where customers enter their mobile number and authenticate using an OTP sent to their mobile device.

If formsOfPayment are passed manually in an array, wrap each item in quotes—for example, "stcPay".

setupPreload object optional

An ApiTransactionDetails class object is used to store transaction details. If provided, transaction details will not be requested from the backend, thereby reducing processing time.

theme object optional

A Theme class object is used for UI customization. All fields are optional and may include values for background colors, text colors, and fonts for various UI components.

For more details, refer to Android Customization Theme.

displaySettings object optional

The displaySettings object accepts a PaymentOptionsDisplaySettings configuration, which defines how payment options are presented to the user during checkout. For more details, refer to the Payment Options Display Mode section.

successCallback, errorCallback, and successCallback unit required

Callback functions are used to retrieve the payment status. These must be provided directly to the Checkout initialization function. For more information, please check here.

Payment Options Display Mode

The SDK provides flexible customization for how payment options are displayed. It supports the following optional parameters:

• paymentOptionsListMode: Determines the layout style—either BottomSheet (default) or List.

  • BottomSheet: This is the default layout used in previous SDK versions.

  • List: A new layout that shows payment options in a vertical list placed above the Payment Details section and the Pay button.

• paymentOptionsListCount: Sets how many payment options are shown at once (default is 5). Applicable only in List mode.

  • This unsigned integer controls how many payment options are visible simultaneously in List mode.

  • If the number of available options is less than visibleItemsCount, the list automatically resizes to fit the actual number of options.

Passing 0 will cause the SDK to throw an exception. This exception must be caught and handled by the parent application.

• defaultSelectedPgCode: Specifies a payment gateway (PG) code to be pre-selected by default.

  • This field accepts a PG code to auto-select a specific payment option.

  • If the SDK finds a payment method matching the provided PG code, it will be selected by default.

  • If no match is found, no option is selected.

All of these parameters are optional and are demonstrated in the following figures.

Android

The List The List mode is displayed as illustrated in the figure below

A view with a selected payment option

A view with an expanded listExpanded list view

Here is a code sample:

val paymentOptionsDisplayMode =
  if (showPaymentOptionsList) Checkout.PaymentOptionsDisplaySettings.PaymentOptionsDisplayMode.List(
    visiblePaymentItemsCount = paymentOptionsListCount
  ) else Checkout.PaymentOptionsDisplaySettings.PaymentOptionsDisplayMode.BottomSheet
val paymentOptionsDisplaySettings = Checkout.PaymentOptionsDisplaySettings(
  mode = paymentOptionsDisplayMode,
  defaultSelectedPgCode = defaultSelectedPgCode
)

and passed to Checkout.init builder class via the following object:

.paymentOptionsDisplaySettings(paymentOptionsDisplaySettings)

iOS

The List mode looks like the following

Selected item view

Expanded list view

Here is a code sample:

let paymentOptionsDisplaySettings: PaymentOptionsDisplaySettings =
  if arguments.showPaymentOptionsList {
    PaymentOptionsDisplaySettings(
      mode: .list,
      visibleItemsCount: UInt(arguments.paymentOptionsListCount),
      defaultSelectedPgCode: arguments.defaultSelectedPgCode
    )
  } else {
    PaymentOptionsDisplaySettings(
      mode: .bottomSheet,
      defaultSelectedPgCode: arguments.defaultSelectedPgCode
    )
  }

and passed to Checkout.init via the following object:

displaySettings:paymentOptionsDisplaySettings

To see the full function call, please refer the code snippet in the Ottu SDK - Flutter | Example section.