Using an object as an instance variable in a basic Objective C program, I get an "expected specifier-qualifier-list" error -

I am writing a simple program that uses an object * center from an XYPoint class as an Exercise Variable. @ Interface Circle: NSOJject {Int Bidia; XYPoint * center; }

However, I get this error message when compiling the code:

Error: 'Expected specification-eligibility-list' before 'XYPoint' / P>

How can I fix this?

In circle H, you declare the XYPoint class:

  @ Class XYPoint;   
 Then, in the circle, import its full definition:  
  #import "XYPoint.h"