gistfile1.m

@interface SomeClass
{
  ...
}
// Use 'assign' because a meta class is not subject to the normal retain/release lifecycle. 
// It will exist until the application is terminated (Class Initialization -> Application Termination)
// regardless of the number of objects in the runtime that reference it.
@property (nonatomic, assign) id<ExternalUtility> externalUtility
@end