iOS通用应用程序Xcode 4入门技巧

Question

I'm trying to start a universal app using Xcode and I'm totally lost. I started the universal Window based app from the templates. I'm trying to have a UITableViewController for the iPhone, and a UISplitViewController for the iPad. I see 3 appDelegates, and did read this post http://www.kotancode.com/2011/04/05/ios-universal-apps/ , but I'm still really confused. I started by creating a UIViewController subclass in the iPadAppDelegate folder with a .xib. Nothing is in the file yet. Then in the iPadAppDelegate.h:

@property (nonatomic, retain) IBOutlet HomeViewController_iPad *homeViewController;

Dragged a UIViewController in the MainWindow_iPad.xib, changed the class to HomeViewController, and tried dragging an outlet from the MainWindow to the UIViewController and I am not able to connect the HomeViewController.

I thought I could do somthing like this for the iPhoneAppDelegate as well, but I believe I am missing something from the Universal App Template. Can someone give me some advice on how these 3 appDelegates work and how I can get started? TIA

Answer 1

Universal Apps are really simple once you grasp how they work.

The reason there are three AppDelegates is that you usually have one that is the base class for an iPhone and iPod specific app delegate. The entry-point into your iPhone or iPad Application is based on the configuration in your .plist file, if you select the project in xCode 4 it will show you a graphical configuration dialog that will allow you to change those properties. The so called "Main Interface" is independently selectable for iPhone and iPad in the respective deployment section. The Main Nib file does contain a serialized version of the device specific app delegate, which will then be "woken up" when the application is loading. This process is triggered from your Main() method when

UIApplicationMain(argc, argv, nil, nil)

is called. UIApplicationMain does take care of loading the proper NIB file, based on the device it is run on.

Thats all there is.