Access private variables of a class in other project - objective-c

Question

I have a huge Objective-C project which I want to split into several ones in a single WorkSpace. Initially I did it, and code compiled well, but I decided also to move one category of a big class to other project, and now linker doesn't understand the situation:
Undefined symbols for architecture x86_64:
"_OBJC_IVAR_$_MyClass.data", referenced from:
-[MyClass(Viz) someTask] in MyClass+Viz.o
d: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Briefly, my workspace looks like this:
- MyLib project:
MyClass.h
MyClass.m
MyClass+Inner.h
MyClass+Inner.m
- MyApp project:
MyClass+Viz.h
MyClass+Viz.m
MyLib is compiled into MyLib.framework which is used in MyApp. As I said, before moving MyClass+Viz to MyApp project, all the complex logic worked correctly, so there is probably no problem with projects linking. Also, I checked twice that all the files are marked correctly in Build Phases settings section.
This is the MyClass.h file:
#interface MyClass : NSObject
- (instancetype)init;
- (void)public_methods;
#end
This is the MyClass+Inner.h file:
#import "MyClass.h"
#interface MyClass ()
{
// Variables placed here
// so that only class methods can access them
SomeStruct* data;
// other fields ...
}
#end
#interface MyClass (Inner)
- (void)private_methods;
#end
And the MyClass+Viz.m file:
#import "MyClass+Viz.h"
#import "MyClass+Inner.h"
#implementation MyClass (Viz)
- (int)someTask {
return data->length;
// this or any other stuff with
// class variables from MyClass+Inner.h
// leads to "Undefined symbols" by linker
}
#end
How can I make it work, make linker see class' private variables from other project?

Answer 1

First, you should be using #property and not instance variables, generally.
Secondly, you would do something like this using multiple header files and class extensions.
Typcially,
MyClass.h
MyClass_Internal.h
MyClass.m
MyClass_Internal.m (Not typically used)
MyClass.m would import both headers. MyClass.h would define the public interface and MyClass_Internal.h would have a class extension to provide the private interface:
#interface MyClass()
#property(...) Thing *internalThing;
#end