Question

Is there a way to have “private” methods in a superclass (which are not in its header file) and still be able to access these from subclasses?

Answer 1

You could use a custom category, for example:

Stuffy.h

// The "official" header file to be used by almost anyone

@interface Stuffy { 
    int myMember;
}

- (void) somePublicMethod;
@end

Stuffy+Secret.h

// The magic header file, which should only be used by knowledgable people

#import "Stuffy.h"

@interface Stuffy (Secret)
    - (void) _pseudoProtectedMethod;
@end

Stuffy.m

#import "Stuffy+Secret.h"

@implementation Stuffy 

- (void) somePublicMethod {
    // ...
}

@end

@implementation Stuffy (Secret)

- (void) _pseudoProtectedMethod {
    // ...
}

@end

Subclasses of Stuffy can now either import Stuffy.h in their .m files and stick to the public API, or import Stuffy+Secret.h and use the semi-protected stuff.

Note, that Objective-C has no true notion of protected or private methods. Basically, anyone can include Stuffy+Secret.h and use the stuff declared there.