Скачать или смотреть How to Declare Cocoa Classes in Objective-C for Plugin Development

Learn how to correctly declare Cocoa classes in Objective-C so that they are available for other plugins during compilation.
---
This video is based on the question https://stackoverflow.com/q/72392765/ asked by the user 'SteffX' ( https://stackoverflow.com/u/6453049/ ) and on the answer https://stackoverflow.com/a/72436656/ provided by the user 'SteffX' ( https://stackoverflow.com/u/6453049/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to declare Cocoa classes which WILL be available later?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Declare Cocoa Classes for Plugin Development in Objective-C

Developing plugins in Objective-C can be a thrilling experience, especially when experimenting with Cocoa classes. However, it often leads to frustrating moments when those classes aren't recognized by the compiler. If you've ever found yourself dealing with missing class errors while trying to compile your plugins, you're not alone. Let’s break down the problem and then explore a straightforward solution to ensure your Cocoa classes are properly declared and available for use.

Understanding the Problem

In plugin development, particularly when writing dynamic libraries (dylib), it's common to create Cocoa classes that other plugins may want to utilize. The challenge arises when the first plugin needs to declare those classes, only to find that subsequent plugins fail to compile due to missing class definitions. This can be particularly daunting for junior developers who may be new to Objective-C.

Common Issues Include:

Missing Class Errors: These errors occur when a class that is expected to be available isn't found during compilation.

Insufficient Visibility: Simply providing header files or using @ class may not be enough for the compiler to recognize the classes.

The Solution: Weak-Linking Dynamic Libraries

Fortunately, there's an elegant solution to this issue: weak-linking against the dynamic library inside your first plugin. This allows the compiler to understand that the classes are defined in a separate dylib which will be loaded at runtime.

Step-by-Step Guide on Weak-Linking

Create Your Dynamic Library: Start with defining your Cocoa classes within your first plugin, compiling it into a dynamic library (dylib).

Embed it in Your Application: Even if your dylib is situated in a zip archive, the main application will handle loading it into memory, making the classes accessible for other plugins.

Declare Weak Links: To inform the compiler that certain classes will be available at runtime, you need to specify weak links in your code. This is typically done in your build settings where you can set your library's dependency as a weak link.

How to do this in Xcode:

Open your project settings.

Navigate to Build Settings.

Look for the Linking section and find Other Linker Flags.

Add -weak_library followed by the path to your dylib.

Benefits of Weak-Linking

Avoid Compilation Errors: This method helps ensure that your plugins can compile without running into errors due to missing classes.

Cleaner Code: By not cluttering your code with unnecessary checks for class existence, your codebase remains cleaner and more maintainable.

Flexibility: Weak-linking allows for more modular plugin development since classes can evolve independently without breaking dependencies.

Conclusion

Navigating the intricacies of Objective-C, especially in plugin development, can seem daunting at first glance. However, with the strategy of weak-linking dynamic libraries, you can effectively declare Cocoa classes that will be available for other plugins at runtime. By following the steps outlined, you can save valuable time and avoid the frustrations typically encountered during the compilation process. Happy coding!