Using the Xcode Source Editor
The main tool you use to write code for an iPad application is the Xcode Source editor, which appears as the Standard editor pane in the editor area on the right side of the Xcode Workspace window after you select a source code file in the Project navigator. It also appears as the Assistant editor in a second pane if you click the Assistant Editor button — the middle Editor selector button in the top-right corner of the Workspace window.
Apple has gone out of its way to make the Source editor as useful as possible by including the following:
Code completion: Code completion is a feature of the editor that shows symbols — arguments, placeholders, and suggested code — as you type statements. Code completion can be really useful, especially if you’re like me and forget exactly what the arguments are for a function. When code completion is active (as it is by default), Xcode uses the text you typed — as well as the context within which you typed it — to provide inline suggestions for completing what it thinks you’re going to type. You can accept inline suggestions by pressing Tab or Return. You can also see a pop-up list of suggestions by clicking an item in the suggestion list or clicking the up and down arrows to select an item. As you do so, the inline suggestion changes depending on what you selected. Press the Esc key, or Control+spacebar, to cancel ...