feat: add Objective-C wrapper for Facebook integration

[SKannaniOS]

Description

This PR adds Objective-C compatibility to the Facebook Swift integration by introducing a wrapper class that exposes the existing FacebookIntegration to Objective-C projects. This allows Objective-C apps to seamlessly integrate Facebook App Events with RudderStack using the device mode integration.

The wrapper class ObjCFacebookIntegration (exposed as RSSFacebookIntegration in Objective-C) provides a complete interface for track, identify, and screen events while maintaining proper error handling patterns expected in Objective-C code.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactor/optimization

Implementation Details

• Added ObjCFacebookIntegration.swift containing the Objective-C wrapper class
• The wrapper class conforms to ObjCIntegrationPlugin and ObjCStandardIntegration protocols from RudderStackAnalytics SDK
• Implemented all required integration methods:
  • init() - Initializes the underlying FacebookIntegration
  • getDestinationInstance() - Returns the Facebook App Events SDK instance
  • createWithDestinationConfig:error: - Creates and configures the Facebook SDK with NSError-based error handling
  • updateWithDestinationConfig:error: - Updates configuration with NSError-based error handling
  • reset() - Clears user ID and user data from Facebook App Events
  • track: - Processes track events by converting ObjCTrackEvent to TrackEvent
  • identify: - Processes identify events by converting ObjCIdentifyEvent to IdentifyEvent
  • screen: - Processes screen events by converting ObjCScreenEvent to ScreenEvent
• Used @objc(RSSFacebookIntegration) attribute to expose the class with a user-friendly name in Objective-C
• Updated README.md to indicate full Swift and Objective-C support

Checklist

• I have added tests that prove my fix is effective or that my feature works.
• I have added the necessary documentation (if appropriate).
• I have ensured that my code follows the project's code style.
• I have checked for potential performance impacts and optimized if necessary.
• I have checked the code for security issues.
• I have updated the changelog (if required).

How to test?

1. Create an Objective-C iOS project
2. Add the RudderIntegrationFacebook package via Swift Package Manager
3. Import the module and configure the integration:

@import RudderIntegrationFacebook;

RSSConfigurationBuilder *builder = [[RSSConfigurationBuilder alloc] initWithWriteKey:@"<WriteKey>"
                                                         dataPlaneUrl:@"<DataPlaneUrl>"];
RSSAnalytics *analytics = [[RSSAnalytics alloc] initWithConfiguration:[builder build]];

RSSFacebookIntegration *facebookIntegration = [[RSSFacebookIntegration alloc] init];
[analytics addPlugin:facebookIntegration];

4. Verify that track, identify, and screen events are forwarded to Facebook App Events

Breaking Changes

None. This is a purely additive change that does not affect existing Swift implementations.

Maintainers Checklist

• The code has been reviewed.
• CI tests have passed.
• All necessary documentation has been updated.

Screenshots (if applicable)

N/A - No UI changes

Additional Context

• This feature enables developers working with Objective-C codebases or mixed Swift/Objective-C projects to use the Facebook integration without needing to write Swift bridging code themselves.
• The wrapper delegates all functionality to the underlying Swift FacebookIntegration class, ensuring consistent behavior across both languages.

[Copilot]

Pull request overview

This PR adds Objective-C compatibility to the Facebook Swift integration by introducing a wrapper class (ObjCFacebookIntegration) that exposes the existing Swift FacebookIntegration to Objective-C projects. The wrapper delegates all functionality to the underlying Swift implementation, ensuring consistent behavior across both languages.

Changes:

• Added ObjCFacebookIntegration.swift with a complete Objective-C wrapper implementing ObjCIntegrationPlugin and ObjCStandardIntegration protocols
• Updated README.md to indicate full Swift and Objective-C support

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
Sources/RudderIntegrationFacebook/ObjCFacebookIntegration.swift	New wrapper class that exposes FacebookIntegration to Objective-C with proper error handling, event conversion, and comprehensive documentation
README.md	Added note about Swift and Objective-C support

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