Simple nib file question

Question

I believe that all the examples I've seen of nib/xib files have been connections to the corresponding controller or view files, or to the app delegate and the main window,
Please correct me if I'm wrong, I might just be tired and missing an important clue
I'm using a Utility Application template, and have most of my work done using the MainView and MainViewController. I'd like to now work on the FlipsideView and FlipsideViewController to display and/or manipulate status and options, which is already in instances/classes in the MainView and MainViewController type.
How do I access data in the other View, ViewController, or app delegate by connecting buttons and fields from my FlipsideView?
This may be a "duh! Oh Yeah" question/answer, as in just examine how the FlipsideView is connected to the MainViewController. However, I could use a little leading and pointing here.
In my test app, I've already created a number of labels for static info, or to hold the value of a field in the other class instances. I'm just trying to figure out how to make the connections. I do have a few of the data elements setup with IBOutlets already.

Answer 1

When the controllers of separate nibs need to communicate with each other, the best solution depends on the structure of the program and how many controllers are involved. Luckily the discussion gets much easier if we restrict it to the nibs in the Utility template. However, the Utility template that came with SDK 3.0 is quite different from the 2.x version. I'll start with 3.0.
With the 3.0 Utility template you have a built in communication channel because the flipside view controller is the modal child of the main view controller. That means flipsideViewController.parentController points to mainViewController. And mainViewController.modalViewController points to flipsideViewController.
So for example, if textField1 is in the main view, and label1 is in the flipside view:
// in FlipsideViewController.m
self.label1.text = parentViewController.textField1.text;
Note however that communication in the other direction is limited to the time the flipside view is active. While mainViewController will always exist when the flipside view covers it, the flipsideViewController is released when its view is dismissed. So in order to export info from flipside to main, you might have the flipside controller save the data ahead of time. For example if the mainViewController needs the text from label2 which is on the flipside:
// in FlipSideController.m
parentViewController.copyOfLabel2 = self.label2.text;
You also mentioned getting data from the app delegate. The app delegate is accessible from any object in the program precisely because it's "the shared application object's delegate". So for example, if mainViewController is an instance variable (with a matching property) of the app delegate, a method of any object in the program could obtain a pointer to the mainViewController, and thus any objects in its view:
// in AnyClass.m
#include "MyAppDelegate.h"
#include "MainViewController.h"
- (NSString*)getTextField1 {
myAppDelegate *delegate = [UIApplication sharedApplication].delegate;
MainViewController *mainViewController = delegate.mainViewController;
return mainViewController.textField1.text;
The solution for the 2.x version of the Utility template is based on the fact that both the main and flipside controllers are children of a root view controller. I'll wait to find out which version you have before dealing with the 2.x template.
Hope that helps!
- Ray