Fix ios Build

Author: porter-stripe

ios/StripeSdkImpl+Checkout.swift

@@ -5,6 +5,7 @@
 //  Created by Nick Porter on 4/29/26.
 //
 
+import Combine
 import Foundation
 @_spi(CheckoutSessionsPreview) import StripePaymentSheet
 
@@ -13,6 +14,28 @@ extension StripeSdkImpl {
         Mappers.mapFromCheckoutState(checkout.state)
     }
 
+    /// Forwards every `Checkout` state change to JS. We listen on `$state`
+    /// instead of `CheckoutDelegate` since the delegate misses the loading
+    /// transitions, but `$state` fires on every assignment.
+    @MainActor
+    internal func observeCheckoutState(
+        _ checkout: Checkout,
+        sessionKey: String
+    ) {
+        checkoutStateCancellables[sessionKey]?.cancel()
+
+        checkoutStateCancellables[sessionKey] = checkout.$state
+            // JS already has the initial state from `initCheckoutSession`.
+            .dropFirst()
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] state in
+                self?.emitter?.emitCheckoutSessionDidChangeState([
+                    "sessionKey": sessionKey,
+                    "state": Mappers.mapFromCheckoutState(state),
+                ])
+            }
+    }
+
     @objc(initCheckoutSession:configuration:resolver:rejecter:)
     public func initCheckoutSession(
         clientSecret: String,
@@ -36,6 +59,7 @@ extension StripeSdkImpl {
                 let sessionKey = UUID().uuidString
 
                 self.checkoutInstances[sessionKey] = checkout
+                self.observeCheckoutState(checkout, sessionKey: sessionKey)
 
                 resolve([
                     "sessionKey": sessionKey,

ios/StripeSdkImpl.swift

@@ -1,4 +1,5 @@
 import AuthenticationServices
+import Combine
 import Foundation
 import PassKit
 @_spi(DashboardOnly) @_spi(STP) import Stripe
@@ -69,6 +70,8 @@ public class StripeSdkImpl: NSObject, UIAdaptivePresentationControllerDelegate {
     internal var paymentSheet: PaymentSheet?
     internal var paymentSheetFlowController: PaymentSheet.FlowController?
     internal var checkoutInstances: [String: Checkout] = [:]
+    /// One Combine subscription per active `Checkout`, keyed by `sessionKey`.
+    internal var checkoutStateCancellables: [String: AnyCancellable] = [:]
     var paymentSheetIntentCreationCallback: ((Result<String, Error>) -> Void)?
     var paymentSheetConfirmationTokenIntentCreationCallback: ((Result<String, Error>) -> Void)?