Swift class in ObjC Project : "Receiver 'MySwift' for class message is a forward declaration" error even after adding @obj and open prefixes

>> In one of my Objective-C class header (Say, MyObjCClass.h), I do the forward declaration for MySwiftClass.

What specifically is that line of code?

>> Receiver 'SocketIOClient' for class message is a forward declaration

This is the actual name of the class that you referred to as MySwiftClass? It's OK to suppress the actual name for the purposes of posting here, but your description is a bit confusing because inconsistent.

>> Imported MyProject-Swift.h in the MyObjCClass.m file.

What is the actual content of this file in relation the MySwiftClass type? You don't have to show the members (properties and methods), just the @interface that declares the class, and anything else that's relevant.

Note that if MyProject-Swift.h contains an @interface for MySwiftClass, and it's #imported into MyObjCClass.m, then it's "impossible" that you should get a forward declaration error on the Obj-C side. The error suggests that there's something else wrong, such as a subtle typo in one of the declared class names, or that there are two MyProject-Swift.h files in different locations, or something like that.

Edit: Oh, one more thing I meant to ask. Is this an app target, or something else (like a framework)?

Thanks for the reply.

MyProject-Siwft.h is the bridging header from Swift to Objective-C which is autogenerated by Xcode. It includes all the header definitions for the swift classes, so that they can be used in the Objective-C code. So, does not define specific class interface.

I know, it's an old issue. But, to help other peoples I post my answer.

To create an instance of a swift you need to inherit of NSObject.

class MySwiftClass: NSObject {

}

Sometimes you need to add @objc component behind the class.

@objc class MySwiftClass: NSObject {

}