The Software Development Kit (SDK) gives you the opportunity to develop your apps without tying your brain up in knots. You can rapidly get a user interface up and running to see what it looks like. The idea here is to add your code incrementally — step by step — so that you can always step back and see how what you just did affects the Big Picture.

Your general steps in development should look something like this:

In this chapter, you start at the very beginning, with the very first step, which is Xcode. (Starting with Step 1? What a concept!) And the first step of the first step is to create your first project.

To develop an iPhone app, you work in what's called an Xcode project. So, time to fire one up. Here's how it's done:

To develop an iPhone app, you have to work within the context of an Xcode project. It turns out that you do most of your work on projects using a Project window very much like the one in Figure 4-3. If you have a nice, large monitor, expand the Project window so you can see everything in it as big as life. This is, in effect, Command Central for developing your iPhone app; it displays and organizes your source files and the other resources needed to build your app.

If you take another peek at Figure 4-3, you see the following:

To see how the Editor view works, check out Figure 4-5, where I've clicked the Main View folder in the Groups & Files list, and the MainView.h class in the Detail view. You can see the code for the class in the Editor view.

Right under the Lock button (refer to Figure 4-5) is a tiny windowshade icon that lets you split the Editor view. Click it to look at the interface and implementation files at the same time, or even the code for two different methods in the same or different classes.

Figure 4-5. The MainView.h file in the Editor view.

The first item in the Groups & Files view, as you can see in Figure 4-5, is labeled DeepThoughts. This is the container that contains all the source elements for the project, including source code, resource files, graphics, and a number of other pieces that will remain unmentioned for now (but I get into those in due course). You can see that this project container has seven distinct groups — Main view, Flipside view, Application Delegate, Other Sources, Resources, Frameworks, and Products. Here's what gets tossed into each group:

When you have a lot files, you'll have better luck finding things if you create subgroups within the Main View, Flipside View, and/or Resources groups, or even whole new groups. You create subgroups (or even new groups) in the Groups & Files list by choosing New Project

It's really a blast to see what you get when you build and run a project that you yourself created using a template from the Project window. Doing that is relatively simple:

After it's launched in the Simulator, your first app looks a lot like what you see in Figure 4-8. You should see the status bar and a gray window with the i information button (the hallmark of an app built from the Utility template), but that's it. You can also see the Hardware menu in Figure 4-8, which I explain next.

Now click on the i information button to see the flipside view, as shown in Figure 4-9. Whoa! You now have a standard iPhone app flipside view, complete with a Done button. Click the Done button to go back to the Main view. (I know, big deal . . . but about half the work of designing the DeepThoughts app is already done, thanks to the Utility template, and you continue adding functionality in Book III.)

Figure 4-8. The Deep Thoughts app's Main view in the Simulator.

Figure 4-9. The Deep Thoughts app's flipside view in the Simulator.

When you run your app, Xcode installs it on the iPhone Simulator (or a real iPhone device if you specified the device as the active SDK) and launches it. Using the Hardware menu and your keyboard and mouse, the Simulator mimics most of what a user can do on a real iPhone, albeit with some limitations that I point out shortly.

Uninstalling apps and resetting your device

You uninstall applications on the Simulator the same way you'd do it on the iPhone, except you use your mouse instead of your finger.

1. On the Home screen, place the pointer over the icon of the app you want to uninstall and hold down the mouse button until all of the app icons start to wiggle.

2. Click the app icon's Close button — the little x that appears in the upper-left corner of the icon — to make the app disappear.

3. Click the Home button — the one with a little square in it, centered below the screen — to stop the other app icon's wiggling and finish the uninstallation.

You can also move an app's icon around by clicking and dragging with the mouse.

To reset the Simulator to the original factory settings — which also removes all the apps you've installed — choose iPhone Simulator

Xcode gives you options galore; I'm guessing you won't change any of them until you have a bit more programming experience under your belt, but a few options are actually worth thinking about now.

You can also have the Editor show line numbers. If you click Text Editing in the Xcode Preferences toolbar to show the Text Editing pane, you can select the Show Line Numbers check box under Display Options. I don't take this step now, but having line numbers visible becomes very useful in Chapter 1 of Book IV.

Interface Builder is a great tool for graphically laying out your user interface. You can use it to design your app's user interface and then save what you've done as a resource file, which is then loaded into your app at runtime. This resource file is then used to automatically create the single window, as well as all your views and controls, and some of your app's other objects — view controllers, for example. (For more on view controllers and other application objects, check out Chapter 5 in this minibook.)

Here's how Interface Builder works:

Figure 4-13. Selecting and double-clicking the Flipside View.xib file.

What you see after double-clicking are the windows as they were the last time you left them. If this is the first time you've opened Interface Builder, you see windows that look something like those in Figure 4-14.

Not surprisingly, the Flipside view window in Figure 4-14 shows the flipside view, which looks exactly as it did in the iPhone Simulator. (Refer to Figure 4-9.)

Figure 4-14. The Flipside View.xib file in Interface Builder.

Interface Builder supports two file types: an older format that uses the extension .nib and a newer format that utilizes the extension .xib. The iPhone project templates all use .xib files. Although the file extension is .xib, everyone still calls them nib files. The term nib and the corresponding file extension .xib are acronyms for NeXT Interface Builder. The Interface Builder application was originally developed at NeXT Computer, whose OPENSTEP operating system was used as the basis for creating Mac OS X.

The window labeled FlipsideView.xib (the top center window in Figure 4-14) is the nib's main window. It acts as a table of contents for the nib file. With the exception of the first two icons (File's Owner and First Responder), every icon in this window (in this case, there's only one, but you'll find more as you get into nib files) represents a single instance of an Objective-C class that will be created automatically for you when this nib file is loaded.

If you were to take a closer look at the three objects in the FlipsideView.xib file window — and if you had a pal who knew the iPhone backwards and forwards — you'd find out the following about each object:

If you take another look at Figure 4-14, you notice two other windows open besides the main window. Look at the Flipside view window that has the word Title in the title bar. That window is the graphical representation of the View icon. If you close the Flipside view window and then double-click the View icon, this window opens again. This window is your canvas for creating your user interface: It's where you drag user-interface elements such as buttons and text fields. These objects come from the Library window (the leftmost window in Figure 4-14).

The Library window contains your palette — the stock Cocoa Touch objects that Interface Builder supports. Dragging an item from the Library to the Flipside view window adds an object of that type to the View (and remember, as subview).

Tip

If you happen to close the Library window, whether by accident or by design, you can get it to reappear by choosing Tools

Finally, at what may seem at long last (although it's really been only a few pages), you're ready to look behind the screen and see exactly how an iPhone app works.

So take a break if you need to, but come back ready to explore.