What is the best way to show a user that he is in offline mode? Does Apple provide anything like a toolbar icon or what would be the best practice on that?
Just use an alertview with a message notifying the user that he has no internet available.
Example:
UIAlertView *someError = [[UIAlertView alloc] initWithTitle: @"Network error"
message: @"Error sending
your info to the server"
delegate: self
cancelButtonTitle: @"Ok"
otherButtonTitles: nil];
[someError show];
[someError release];
I'm not sure if this is what you aim for but it is a suggestion.