how to access NSObject class from naviagation based app?

Im thinking a program that has made up by navigation bar with multiple views. so basically I want to access data(& storing data) to one same object class through the whole stack of navigation. for ex开发者_开发技巧ample, 1. choose a picture from firstview, store the picture to the object class. 2. change to other view and access the picture from the smae object class. 3. as a next step on the other view, also can access and store the data to this object class.

what I want to know now is how to maintain and access the same file from the all different levels of the program. please give me some tips!

---

You can make the UIImageView or other NSObject a property of the rootViewController, and then access it by:

AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
UIViewController *theRootViewController = appDelegate.rootViewController;
NSObject *myObject = theRootViewController.myobject;

However, if what you're passing is an NSArray or BOOL or float or int, then you can also consider using NSUserDefaults to save and load from anywhere within the app.