> ## 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. # Installments > Get notified when the shopper selects an installment option in the card form on Web, iOS, and Android Register the optional `onInstallmentSelected` callback to keep your cart total in sync with the installment plan the shopper picks in the card form. The SDK notifies you when a default installment is pre-selected, every time the shopper changes the selection, and when the plan is recalculated (for example, after a BIN change). The callback is optional on all platforms: if you don't register it, the SDK behavior is unchanged. Exceptions thrown inside your callback are caught by the SDK and never interrupt the payment flow. | Platform | Available from | Where to register | | -------- | -------------- | ---------------------------------------------------- | | Web | SDK `1.6.7` | `card.onInstallmentSelected` in `startCheckout` | | iOS | SDK `2.21.0` | `onInstallmentSelected(_:)` on `YunoPaymentDelegate` | | Android | SDK `2.20.0` | `onInstallmentSelected` parameter of `startCheckout` | ## Implementation Pass the callback inside the `card` options of `startCheckout`: ```javascript theme={"theme":{"light":"github-dark","dark":"github-dark-dimmed"}} await yuno.startCheckout({ checkoutSession: session.checkout_session, elementSelector: '#payment-form', countryCode: 'BR', card: { onInstallmentSelected: ({ installment, label, amount, isMerchantInstallment }) => { // Update your cart total, e.g. with amount?.total_value console.log('Installment selected:', { installment, label, amount, isMerchantInstallment }) }, }, // ... }) ``` The callback receives a single object argument: ```typescript theme={"theme":{"light":"github-dark","dark":"github-dark-dimmed"}} type OnInstallmentSelected = (args: { installment: number label: string amount?: { currency: string value: string total_value: string } additionalData?: Record isMerchantInstallment: boolean }) => void ``` | Field | Type | Description | | ----------------------- | --------- | ----------------------------------------------------------------------------------------------------------------------------------------------- | | `installment` | `number` | Number of installments selected (e.g. `3`). | | `label` | `string` | The exact installment label rendered in the form, localized (e.g. `3x de R$875.00 - Total R$2,625.00`). | | `amount` | `object` | Optional. `currency`, `value`, and `total_value` as raw strings, exactly as reported by the installments plan. | | `additionalData` | `object` | Reserved for future use. Currently always `undefined`. | | `isMerchantInstallment` | `boolean` | `true` when the selected option was supplied by your own `onGetInstallments` callback (merchant installments); `false` for Yuno-provided plans. | Firing semantics: * Fires with the current selection as soon as the plan renders and a default installment is pre-selected, so your total is correct from first paint. * Fires on every selection the shopper makes. * Re-fires the current selection when the available options change (for example, a BIN change recalculates the plan). * Does not fire when installments stop being available — there is no clear notification on Web. * Works across all card flows, including secure fields and Click to Pay. Implement the optional `onInstallmentSelected(_:)` method of `YunoPaymentDelegate`: ```swift theme={"theme":{"light":"github-dark","dark":"github-dark-dimmed"}} class ViewController: UIViewController, YunoPaymentDelegate { // ... required YunoPaymentDelegate implementation ... func onInstallmentSelected(_ installmentSelected: YunoInstallmentSelected?) { guard let installmentSelected else { // Installments are no longer available — restore your base total return } // Update your cart total, e.g. with installmentSelected.amount?.totalValue } } ``` The method receives a `YunoInstallmentSelected?` payload: ```swift theme={"theme":{"light":"github-dark","dark":"github-dark-dimmed"}} @objc public final class YunoInstallmentSelected: NSObject { @objc public let installment: Int @objc public let label: String @objc public let amount: YunoInstallmentAmount? @objc public let additionalData: [String: Any]? } @objc public final class YunoInstallmentAmount: NSObject { @objc public let currency: String @objc public let value: String @objc public let totalValue: String } ``` | Field | Type | Description | | ---------------- | ------------------------ | --------------------------------------------------------------------------------------------------------- | | `installment` | `Int` | Number of installments selected (e.g. `3`). | | `label` | `String` | The exact installment label rendered in the form, localized (e.g. `3x of R$ 500,31 - Total R$ 1.500,93`). | | `amount` | `YunoInstallmentAmount?` | `currency`, `value`, and `totalValue` as raw strings, exactly as reported by the installments plan. | | `additionalData` | `[String: Any]?` | The `additional_data` object of the selected option, when the installments service provides it. | Firing semantics: * Fires once when a default installment is pre-selected as the plan loads, so your total is correct from first paint. * Fires on every selection the shopper makes, and with the recalculated default after the plan changes (for example, a BIN change). * Fires once with `nil` when a previously reported selection no longer applies (for example, the shopper switches to a card without installments) — restore your base total. It is never called with `nil` before the first selection is reported. * Delivered on the main thread. The method is optional — omitting it keeps the SDK behavior unchanged. Pass the callback when calling `startCheckout`: ```kotlin theme={"theme":{"light":"github-dark","dark":"github-dark-dimmed"}} startCheckout( checkoutSession = "checkout_session", countryCode = "country_code_iso", callbackPaymentState = { state, subState -> /* ... */ }, onInstallmentSelected = { selection -> if (selection != null) { // Update your cart total, e.g. with selection.amount?.totalValue } else { // Installments are no longer available — restore your base total } }, ) ``` The callback receives an `InstallmentSelected?` payload: ```kotlin theme={"theme":{"light":"github-dark","dark":"github-dark-dimmed"}} data class InstallmentSelected( val installment: Int, val label: String, val amount: InstallmentAmount? = null, val additionalData: Map? = null, ) data class InstallmentAmount( val currency: String, val value: String, val totalValue: String, ) ``` | Field | Type | Description | | ---------------- | -------------------- | ------------------------------------------------------------------------------------------------------- | | `installment` | `Int` | Number of installments selected (e.g. `3`). | | `label` | `String` | The exact installment label rendered in the form, localized (e.g. `3x de R$875.00 - Total R$2,625.00`). | | `amount` | `InstallmentAmount?` | `currency`, `value`, and `totalValue` as raw strings, exactly as reported by the installments plan. | | `additionalData` | `Map?` | Reserved for future use. Currently always `null`. | Firing semantics: * Fires once when a default installment is pre-selected as the plan renders, so your total is correct from first paint. * Fires on every selection the shopper makes, and with the recalculated default after the plan changes (for example, a BIN change). * Fires once with `null` when installments stop being available after a selection was already reported (for example, the shopper switches to a card without installments) — restore your base total. * Does not fire when the card form renders without installments. The callback runs on the main thread, and registering no callback keeps the SDK behavior unchanged.