is paper examines, the iOS development landscape underwent a significant transformation with the introduction of Swift, a modern programming language designed to replace Objective-C. Swift offered developers a safer, more expressive syntax and improved performance. Despite Swift's rapid adoption, Objective-C remained deeply embedded in existing applications and frameworks. This dual-language ecosystem allowed developers to leverage Objective-C's extensive libraries while adopting Swift for new projects. Tools like bridging headers facilitated interoperability, enabling teams to incrementally transition to Swift without abandoning their Objective-C codebases. This paper explores the coexistence strategies, benefits, challenges, and impact of using both languages concurrently, highlighting how this gradual evolution influenced iOS app development practices.

Objective-C, Swift Programming Language, Interoperability, iOS Development, Programming Language Transition.