Wire custom callbacks through getPaywall

[yusuftor]

Changes in this pull request

• Adds an optional onCustomCallback parameter to Superwall.getPaywall(forPlacement:params:paywallOverrides:delegate:onCustomCallback:) so paywalls retrieved for embedding can handle custom webview callbacks. Previously this was only wired up through register(), which presents the paywall in its own UIWindow — embedding code (e.g. SwiftUI onboarding flows that need to layer their own UI over the paywall) had no way to receive callbacks and the webview always got a failure result.
• Extends PaywallViewControllerDelegateAdapter with an onCustomCallback closure and registers/unregisters it with the existing CustomCallbackRegistry from PaywallViewController (init, delegate.didSet, deinit). Reuses the same registry as the register() path, so the underlying message-handler dispatch in PaywallMessageHandler.handleRequestCallback is unchanged.
• Bumps version to 4.15.1 (Constants.swift, podspec, CHANGELOG).
• Motivated by Pylon #18179.

Tests

Adds CustomCallbackGetPaywallTests with 4 tests covering: handler registered when adapter has one; no registration when handler is nil; reassigning the delegate updates registration (and delegate = nil clears it); deinit unregisters. Updates existing test mocks (SurveyManagerTests, PresentPaywallOperatorTests, WebEntitlementRedeemerTests, TrackingLogicTests) to pass the new customCallbackRegistry: init parameter.

Checklist

• All unit tests pass.
• All UI tests pass.
• Demo project builds and runs on iOS.
• Demo project builds and runs on Mac Catalyst.
• Demo project builds and runs on visionOS.
• I added/updated tests or detailed why my change isn't tested.
• I added an entry to the CHANGELOG.md for any breaking changes, enhancements, or bug fixes.
• I have run swiftlint in the main directory and fixed any issues.
• I have updated the SDK documentation as well as the online docs.
• I have reviewed the contributing guide

🤖 Generated with Claude Code

Greptile Summary

This PR wires onCustomCallback through getPaywall() so embedded paywalls can receive custom webview callback results instead of always getting a failure. It extends PaywallViewControllerDelegateAdapter with the closure and manages registration/unregistration with the shared CustomCallbackRegistry via a new syncCustomCallbackRegistration() helper called from init, delegate.didSet, and deinit.

Confidence Score: 5/5

Safe to merge; the one concern is a low-probability cross-path interference scenario that is a P2 design suggestion, not a blocking defect.

All findings are P2. The unconditional unregister in deinit / syncCustomCallbackRegistration() only becomes a problem when both register() and getPaywall() are used simultaneously with the same paywall identifier, which is an unusual usage pattern. Core logic, threading, and test coverage are all solid.

PaywallViewController.swift — the syncCustomCallbackRegistration / deinit unregister interaction warrants a second look if the two presentation paths are ever exercised concurrently on the same paywall identifier.

Important Files Changed

Filename	Overview
Sources/SuperwallKit/Paywall/View Controller/PaywallViewController.swift	Adds customCallbackRegistry dependency and syncCustomCallbackRegistration(); the unconditional unregister in deinit and the else branch can silently evict a handler registered by the register() path.
Sources/SuperwallKit/Paywall/View Controller/Delegates/PaywallViewControllerDelegateAdapter.swift	Adds onCustomCallback closure to the adapter with a default-nil init parameter; clean, minimal change.
Sources/SuperwallKit/Paywall/Presentation/Get Paywall/PublicGetPaywall.swift	Threads new onCustomCallback parameter through both the completion-block and async getPaywall overloads; properly defaults to nil for backwards compatibility.
Tests/SuperwallKitTests/Paywall/Presentation/CustomCallbackRegistryTests.swift	New test suite covering registration on init, nil handler, delegate reassignment, and deinit unregistration — good coverage of the happy paths.
Sources/SuperwallKit/Dependencies/DependencyContainer.swift	Passes customCallbackRegistry to PaywallViewController init; mechanical, correct change.

Sequence Diagram

sequenceDiagram
    participant Caller
    participant Superwall
    participant PaywallViewControllerDelegateAdapter
    participant PaywallViewController
    participant CustomCallbackRegistry
    participant WebView

    Caller->>Superwall: getPaywall(forPlacement:onCustomCallback:)
    Superwall->>PaywallViewControllerDelegateAdapter: init(swiftDelegate:objcDelegate:onCustomCallback:)
    Superwall->>PaywallViewController: init(...customCallbackRegistry:)
    PaywallViewController->>PaywallViewController: syncCustomCallbackRegistration()
    PaywallViewController->>CustomCallbackRegistry: register(paywallIdentifier:handler:)

    Caller->>Caller: embed / present PaywallViewController

    WebView->>PaywallMessageHandler: handleRequestCallback
    PaywallMessageHandler->>CustomCallbackRegistry: getHandler(paywallIdentifier:)
    CustomCallbackRegistry-->>PaywallMessageHandler: handler closure
    PaywallMessageHandler->>PaywallViewControllerDelegateAdapter: onCustomCallback(callback)
    PaywallViewControllerDelegateAdapter-->>PaywallMessageHandler: CustomCallbackResult

    Caller->>PaywallViewController: delegate = nil / deinit
    PaywallViewController->>CustomCallbackRegistry: unregister(paywallIdentifier:)

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Prompt To Fix All With AI

This is a comment left during a code review.
Path: Sources/SuperwallKit/Paywall/View Controller/PaywallViewController.swift
Line: 292-295

Comment:
**Unconditional `unregister` in `deinit` may evict a `register()` handler**

`deinit` always calls `customCallbackRegistry.unregister(paywallIdentifier:)`, even when this VC was created via `getPaywall()` with `onCustomCallback: nil` (i.e., it never registered anything). The same applies to the `else` branch in `syncCustomCallbackRegistration()`. Because the registry is shared with the `register()` path, a sequence like:

1. `register()` presents paywall "abc" → handler stored under key "abc"
2. `getPaywall()` is called for the same paywall without `onCustomCallback` → `syncCustomCallbackRegistration()` calls `unregister("abc")`, silently evicting the live `register()` handler

A guard that only unregisters when this VC actually owns the current registration would prevent the cross-path interference:

```swift
private var hasRegisteredCallback = false

private func syncCustomCallbackRegistration() {
  if let handler = delegate?.onCustomCallback {
    customCallbackRegistry.register(paywallIdentifier: paywall.identifier, handler: handler)
    hasRegisteredCallback = true
  } else if hasRegisteredCallback {
    customCallbackRegistry.unregister(paywallIdentifier: paywall.identifier)
    hasRegisteredCallback = false
  }
}

deinit {
  introOfferTokenManager.stopObservingAppLifecycle()
  if hasRegisteredCallback {
    customCallbackRegistry.unregister(paywallIdentifier: paywall.identifier)
  }
}
```

How can I resolve this? If you propose a fix, please make it concise.

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