Question

Question is in title. Code example:

UIViewController <MyProtocol> *viewcontroller = ...;

[viewcontroller methodFromProtocol]; // I expect to be able to call all methods that the protocol defines

//UIViewControllerSubclass implements MyProtocol

UIViewControllerSubclass *viewControllerSubclassWithoutMyProtocol = [[UIViewControllerSubclass alloc] init];
[viewControllerSubclassWithoutMyProtocol methodThatIsNotInTheInterfaceIsDisplayedHere]; // I only expect to be able to call the methods that are defined in this class' interface even though this class implements MyProtocol

Answer 1

Your question isn’t completely clear, but I think you are asking if you can “privately” conform to a protocol?

This can be done by declaring that you conform to the protocol inside the implementation file, rather than the interface file. With view controllers, you can do this in the class continuation that is generated for you automatically in the .m file, otherwise you’ll need to add the class continuation in yourself:

@interface MyVCSubclass () <MyProtocol>

Now, any class that imports only the header file will not know your controller conforms to the protocol.