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First Steps

If you’ve worked with Cocoa and Xcode before, you know that every Cocoa application starts out as a project. A project is simply a repository for all the elements that go into the application, such as source code files, frameworks, libraries, the application’s user interface, sounds, and images. You use Xcode to create and manage your project.

The QTKit capture player application should serve as a good learning example for developers who may be new to Cocoa and QuickTime. If you already know Cocoa, you probably won’t be surprised at how quickly and effortlessly you can build this capture player application.

In this section:

What You Need
Prototype the Capture Player

What You Need

Before you get started with your QTKit capture player project, be sure that you are running Mac OS X v10.5 and have the following items installed on your system:

• Xcode 3 and Interface Builder 3. Note that although you can use Xcode 2.2 to build your project, to take full advantage of the new programming features available, you’ll want to use Xcode 3. Also, Interface Builder 3 provides a new paradigm for working with and building the user interface for your application. Palettes are no longer provided; instead, you’ll work with a new library of controls that are designed to enable you to hook up the components of your user interface with greater ease and efficiency. In the end, you’ll be able to build applications faster and take advantage of this rich, new library of controls.

• The QuickTime Kit framework, which resides in the Mac OS X v10.5 System/Library/Frameworks directory as QTKit.framework.

• An iSight camera connected to your computer.

  Important: The complete sample code discussed in this and the next chapter is available for download at Sample Code: QuickTime Cocoa, as MyRecorder.

  Note: The MyRecorder sample code, as explained in this chapter, will not support DV cameras, which are of type QTMediaTypeMuxed, rather than QTMediaTypeVideo. The next chapter in this programming guide, “Adding Audio Input and DV Camera Support,” explains how you can add code that lets you work with DV cameras and use the QTMediaTypeMuxed type.

Prototype the Capture Player

Interface Builder lets you specify the windows, menus, and views of your application, while Xcode enables you to define the behavior behind them. Interface Builder provides the basic support you need for configuring the items in your user interface. Beyond that, most of the work you do in constructing your application takes place in Xcode.

When designing your application, start by defining your application’s data model in Xcode. Once you’ve constructed a workable data model, you can use Interface Builder to create a set of basic windows, menus, and views for presenting that data. Depending on the complexity of your design, you may also need to create custom views and controls, and then integrate them into Interface Builder and add them to your nib files.

Creating the controller objects and tying them to your data model in your user interface is the final step in the design process.

Of course, you can just jump right in and start assembling windows and menus in Interface Builder. However, using Interface Builder 3, which is the latest iteration, it’s important to have a good understanding of your application’s desired behavior first. Knowing your application’s data model, and knowing what operations will occur on that data, will help you piece together the design elements you need to show in order to convey that information to the end user.

You may want to start by creating a rough sketch of your QTKit capture application. Think of what design elements you want to incorporate into the application. Rather than simply jumping into Interface Builder and doing your prototype there, you may want to visualize the elements first in your rough sketch, as shown in Figure 2-1.

In this design prototype, you can start with three simple objects: a capture view and two control buttons. These will be the building blocks for your application. After you’ve sketched them out, you can begin to think of how you’ll be able to hook them up in Interface Builder and what code you need in your Xcode project to make this happen.

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