documentclass[preview]{standalone}
usepackage{listings,lipsum}
begin{document}
lstset{language=[Objective]C, frame=single}
begin{figure}[h]
   {centering
      begin{lstlisting}
      struct CVMatWrapperImpl;
      @interface CVMatWrapper : NSObject

      @property (nonatomic,readwrite) struct CVMatWrapperImpl* impl; ///< Pointer to struct wrapping the matrix
      @property (nonatomic,readonly) int rows; ///< Number of rows of the wrapped matrix
      @property (nonatomic,readonly) int cols; ///< Number of columns of the wrapped matrix
      -(NSArray*)eulerAngles;
      -(NSString*)description;
      @end
      end{lstlisting}
      caption{PIMPL pattern}
   label{lst:pimpl}}
end{figure}
end{document}

begin{lstlisting}
struct CVMatWrapperImpl;
@interface CVMatWrapper : NSObject

@property (nonatomic,readwrite) struct CVMatWrapperImpl* impl; ///< Pointer to struct wrapping the matrix
@property (nonatomic,readonly) int rows; ///< Number of rows of the wrapped matrix
@property (nonatomic,readonly) int cols; ///< Number of columns of the wrapped matrix
-(NSArray*)eulerAngles;
-(NSString*)description;
@end
      end{lstlisting}