Objective-C #import loop

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You’ve already hinted at the explanation: an #import cycle.

The first thing I’d do is remove the #include and add the following line above the @protocol definition:

@class ServerRequest;

This is a forward class declaration, and can help break the import loop. Check out this SO question for more details. Apple also has a brief explanation in this guide.

Basically, #import‘ing a file causes the compiler to bring the entire text of that file into the file in question, and although #import is “smarter” than #include, it doesn’t mean you’re immune from import errors. The @class declaration is a way to tell the compiler that a class exists without importing the header. It’s appropriate to use when you only need to know about the class name, but don’t care about the methods it provides. Generally, you want to use @class in the .h file and #import in the .m file, where you’re actually interacting with the class.

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