Model-View-Controller-Store - iOS Programming: The Big Nerd Ranch Guide - page 779

// If things went bad, show an alert view
UIAlertView *av = [[UIAlertView alloc]
initWithTitle:@"Error"
message:[err localizedDescription]
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];

[av show];

}

}];

}

Now, we won't be able to build and run for some time, but let's see what will happen ( Fig-
ure 28.6 ) . ListViewController asks BNRFeedStore for the RSS feed and says,
“When you have the feed, do the stuff in this block.” The ListViewController
moves on with its life, and the store gets to work.

Figure 28.6 Flow of Nerdfeed with BNRFeedStore

Look at the code in the block that gets executed if there is no err ; it looks a lot like the
code in ListViewController 's connectionDidFinishLoading: method.