CGRect rect1 
   
   =
   
    [self positionRect:sheep];
CGRect rect2 
   
   =
   
    [self positionRect:cow];

   
   if
   
    (
   
   !
   
   CGRectIsNull(CGRectIntersection(rect1,rect2))) {
 
   
   //
   
   handle collision
   
   

   
    [sheep stopAction:jump_4ever];
}