Add MIGRATING.md update

Author: BrandonStalnaker

MIGRATING.md

@@ -93,6 +93,64 @@ This change only affects users who:
 
 The `MPListenerController` class has been removed. The SDK no longer invokes any listener callbacks.
 
+---
+
+### Source-Based Distribution Changes
+
+As part of the transition from binary (XCFramework) to source-based distribution, several public Swift classes have been converted to Objective-C. This improves compatibility with Swift Package Manager and reduces integration complexity, but may require code changes for Swift users who were referencing Swift-specific type hierarchies.
+
+#### MPRoktEvent Classes Moved to Top-Level
+
+The `MPRoktEvent` subclasses have been converted from Swift nested classes to Objective-C top-level classes. This changes how Swift users reference these types.
+
+**Before (Swift):**
+
+```swift
+let initEvent = MPRoktEvent.MPRoktInitComplete(success: true)
+let readyEvent = MPRoktEvent.MPRoktPlacementReady(placementId: "abc")
+let purchaseEvent = MPRoktEvent.MPRoktCartItemInstantPurchase(...)
+```
+
+**After (Swift):**
+
+```swift
+let initEvent = MPRoktInitComplete(success: true)
+let readyEvent = MPRoktPlacementReady(placementId: "abc")
+let purchaseEvent = MPRoktCartItemInstantPurchase(...)
+```
+
+**Affected Classes:**
+
+| Before (Swift)                              | After (Swift)                   |
+| ------------------------------------------- | ------------------------------- |
+| `MPRoktEvent.MPRoktInitComplete`            | `MPRoktInitComplete`            |
+| `MPRoktEvent.MPRoktShowLoadingIndicator`    | `MPRoktShowLoadingIndicator`    |
+| `MPRoktEvent.MPRoktHideLoadingIndicator`    | `MPRoktHideLoadingIndicator`    |
+| `MPRoktEvent.MPRoktPlacementInteractive`    | `MPRoktPlacementInteractive`    |
+| `MPRoktEvent.MPRoktPlacementReady`          | `MPRoktPlacementReady`          |
+| `MPRoktEvent.MPRoktOfferEngagement`         | `MPRoktOfferEngagement`         |
+| `MPRoktEvent.MPRoktOpenUrl`                 | `MPRoktOpenUrl`                 |
+| `MPRoktEvent.MPRoktPositiveEngagement`      | `MPRoktPositiveEngagement`      |
+| `MPRoktEvent.MPRoktPlacementClosed`         | `MPRoktPlacementClosed`         |
+| `MPRoktEvent.MPRoktPlacementCompleted`      | `MPRoktPlacementCompleted`      |
+| `MPRoktEvent.MPRoktPlacementFailure`        | `MPRoktPlacementFailure`        |
+| `MPRoktEvent.MPRoktFirstPositiveEngagement` | `MPRoktFirstPositiveEngagement` |
+| `MPRoktEvent.MPRoktCartItemInstantPurchase` | `MPRoktCartItemInstantPurchase` |
+
+**Migration Steps:**
+
+1. Find all usages of `MPRoktEvent.MPRokt*` in your Swift code
+2. Remove the `MPRoktEvent.` prefix
+3. Type checking with `is` remains unchanged since they still inherit from `MPRoktEvent`
+
+**Notes:**
+
+- Objective-C users are not affected by this change
+- The `MPRoktEvent` base class still exists and can be used for type checking
+- All initializers and properties remain the same
+
+---
+
 ### Direct Routing Enabled by Default
 
 API requests now route directly to regional endpoints based on your API key prefix: