Storyboards make it easy to pass data from one scene to another via the prepareForSegue:sender: method of the UIViewController class. This method is called when the first scene (the source) is about to transition to the next scene (the destination). The source view controller can implement prepareForSegue:sender: to perform setup tasks, such as passing information to the destination view controller about what it should display in its table view. Listing 3-1 shows one implementation of this method.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{if ([[segue identifier] isEqualToString:@"ShowDetails"]) { MyDetailViewController *detailViewController = [segue destinationViewController];    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];    detailViewController.data = [self.dataControllerobjectInListAtIndex:indexPath.row];} }

A segue represents a one-way transition from a source scene to a destination scene. One of the consequences of this design is that you can use a segue to pass data to a destination, but you can’t use a segue to send data from a destination to its source. To solve this problem, you create a delegate protocol that declares methods that the destination view controller calls when it needs to pass back some data.