free proxy list iPhone application development
A File's Owner proxy object. The File's Owner object is actually the UIApplication instance-File's Owner are discussed later, in "File's Owner."
The Interface Builderdocument contains four items:
A Files Owner proxy object.The Files Owner object is actually the UIApplication instanceFiles Owner arediscussed later, in Files Owner.
A First Responder proxyobject. The First Responder is not used in this tutorial but you can learn moreabout it by reading Event Handling in iPhone Application Programming Guide.
An instance ofHelloWorldAppDelegate set to be the application's delegate. Delegates are discussedin the next section.
A window. The window has itsbackground set to white and is set to be visible at launch. Its this windowthat you see when the application launches.
After the application hasfinished launching, you can perform additional customization. A commonpatternand the one youll follow in the next chapteris illustrated in thisdiagram:
When the application objecthas completed its setup, it sends its delegate anapplicationDidFinishLaunching: message. Rather than configuring the userinterface itself, the delegate typically creates a view controller object (aspecial controller responsible for managing a viewthis adheres to themodel-view-controller design pattern as described in Model-View-Controller).The delegate asks the view controller for its view (which the view controllercreates on demand) and adds that as a subview of the window.
Recap
In this article you created anew project and learned about how the application launch process works. In thenext chapter, youll define and create an instance of a view controller.
Adding a View Controller
In this application youllneed two classes. Xcodes application template provided an application delegateclass and an instance is created in the nib file. You need to implement a viewcontroller class and create an instance of it.
Adding a View Controller Class
View controller objects playa central role in most iPhone OS applications. As the name implies, theyreresponsible for managing a view, but on iPhone OS they also help withnavigation and memory management. Youre not going to use the latter featureshere, but its important to be aware of them for future development. UIKitprovides a special classUIViewControllerthat encapsulates most of the defaultbehavior you want from a view controller. You have to create a subclass tocustomize the behavior for your application.
>> In Xcode, in theproject organizer select either the project (HelloWorld at the top of theGroups and Files list) or the Classes group folderthe new files will be addedto the current selection.
>> Choose File > NewFile and in the New File window. Select the Cocoa Touch Classes group, thenselect UIViewController subclass. In the Options section, choose only With XIBfor user interface.
Note: If you dont see theWith XIB for user interface option, make sure you have installed version 3.2of the iPhone OS SDKXcode should show version 3.2.2 or later.
Selecting With XIB for userinterface means that Xcode creates a nib file to accompany the viewcontroller, and adds it to the project. (Nib files are discussed in detail inthe next chapter.)
>> Click Next, and inthe following screen give the file a new name such as MyViewController (byconvention, class names begin with a capital letter). Make sure that both the.m and .h files are created and that the files are added to your project, asshown here:
>> Press Finish andmake sure that the files were added to your project.
If you look at the new sourcefiles, youll see that stub implementations of various methods are alreadygiven to you. These are all you need for the moment; the next task is to createan instance of the class.
In next article we will learnabout Adding a View Controller Property
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