How to invoke this - (NSArray *)namesOfPromisedFilesDroppedAtDestination:(NSURL *)dragDestination

Hi,
I am implementing drag and drop in table. I want to drag and drop the files from table view to desktop or any other application.
Methods which i implemented in which last two method is not invoking
Please anyone tell that, how to invoke the last two method
- (BOOL)tableView:(NSTableView *)tv writeRows:(NSArray*)items toPasteboard:(NSPasteboard*)pboard

- (NSArray *)namesOfPromisedFilesDroppedAtDestination:(NSURL *)dragDestination

- (void)draggedImage:(NSImage *)anImage endedAt:(NSPoint)aPoint operation:(NSDragOperation)operation