Question

I need to be able to create an interface like you create in C# to enforce a group of classes to implement certain methods.
Is this possible in objective c?

Answer 1

You can create a protocol. it would look something like this:
in MyProtocol.h:

@protocol MyProtocol
-(void)myMethod;
-(void)myMethod2;
@end

in MyClass.h

#import "MyProtocol.h"
@interface MyClass : NSObject<MyProtocol>
@end

If you want to receive objects of a given protocol, you can do so like this:

id<MyProtocol> var;

or

NSObject<MyProtocol> *var;

more info here