Swift!!

As Apple states "The powerful programming language that is also easy to learn".

For iOS, iPadOS, macOS, tvOS, and watchOS, Swift is a potent and user-friendly programming language. Swift offers contemporary features that developers adore, and writing Swift code is interactive and enjoyable. The syntax is short but expressive. Swift code is secure by default and results in blazing-fast software.

To be honest using swift has its own pros and cons when compared to cross platform language as React Native and Flutter. Swift code is converted into machine code that is optimized for current hardware using the exceptionally fast LLVM compiler technology. Additionally, it offers object-oriented capabilities like classes, protocols, and generics, providing the performance and power required by Cocoa and Cocoa Touch developers.

Swift is meant to take the place of C-based languages. The Swift community is still expanding, and the language itself is continually changing. Swift source code is accessible to everyone and can be found on GitHub.

So, to conclude You can use Swift today to create an entirely new application or use Swift code to implement new functionality in your app. Swift code coexists with existing Objective-C files in the same project and has full access to Objective-C APIs, making adoption easier.