Question

I’m receiving the following warning:

Instance method 'method name' not found (return type defaults to 'id')

when this code is invoked:

@protocol SomeProtocol <NSObject> {
    @property (nonatomic, retain) SpecificClassName* someDelegate;
}
...
+ (void) aMethod : (id <SomeProtocol>) object {
    [object.someDelegate doSomeThing]; // warning statement show up here
}

I feel like this is a short coming of the compiler at this point, but that just may be the pot calling the kettle black … does anyone have any feedback on this?

Answer 1

You need to #import the header file for SpecificClassName, in your implementation (.m file).

If you’re going to use the type name SpecificClassName in the header file, a forward declaration @class SpecificClassName will do, but calling a method on the class requires the compiler to know the return type of the method.

If you want to call a method on an instance of SpecificClassName, include the header in which it’s defined.