Copy rows in NSTableView?

Question

I can' copy selected rows from the table when app is running.

Therefore, I try to implement my own method.

I get all data into a NSArray and use writeToFile method

It works but is very inefficient...

Is there a better way to do this? Or there's a built-in method to do so?

Such that when I push command-C, I can copy the value of rows?

Thanks a lot!