create multiview app

1. project: window-based app

2. create view controller:

(1)root controller: manage which view to present

(2)content view controller A

(3)content view controller B

3. create nib file

view xib for content view controller

4. create outlet for root controller in app delegate

add root controller's view in applicationDidFinishLaunching

[window addSubview: myRootViewController.view];

5. in root controller's class

(1)add members for content view contrllers

(2)add IBAction to switch content view

6. in IB, create root controller from View Controller

add view to root view controller

add toolbar to view

set the action of button of toolbar as root controller's switch view method

7. in IB, connect app deletgate's outlet to root controller

8. viewDidLoad: the method called when nib is loaded

note: for different iPhone, maybe need to install new profile again