Worked on the getsentry/sentry-cocoa repository, focusing on improving trace context serialization for Cocoa tracing. Addressed a critical bug by correcting the assignment of the 'sampled' key in SentryTraceContext, which ensures accurate serialization of trace data and reduces potential debugging issues in production environments. Enhanced the robustness of the codebase by adding comprehensive unit tests to validate serialization behavior, confirming that all relevant fields are properly included or omitted based on input data. Utilized Objective-C and Swift for implementation, with a strong emphasis on unit testing and iOS development practices to maintain code quality and reliability throughout the process.