objcMembers

objcMembers is a compiler directive used in Objective-C for specifying that a particular member, such as a method or a property, should be exposed to Objective-C. This is particularly relevant in mixed-language projects where Objective-C code needs to interact with code written in other languages, such as C++ or Swift, that are interoperating with Objective-C.

When you define a class in Objective-C, its methods and properties are automatically available to other Objective-C code. However, if you are using Objective-C++ to bridge Objective-C and C++, or if you are writing Objective-C interfaces for C++ classes, you might need to explicitly mark certain members as objcMembers. This ensures that the Objective-C runtime can see and invoke these members.

For instance, when using Objective-C++ to expose C++ classes to Objective-C, you would typically wrap the C++ class within an Objective-C class. Methods of the C++ class that you wish to call from Objective-C would then be declared as objcMembers within the Objective-C wrapper class. This directive signals to the compiler that these specific members are intended for Objective-C interoperability.

The primary purpose of objcMembers is to facilitate seamless integration between Objective-C and other languages within the Apple development ecosystem. It allows developers to leverage existing Objective-C frameworks and runtime features when working with codebases that incorporate multiple programming languages. Without such directives, members intended for Objective-C interaction might remain inaccessible to the Objective-C runtime.