Like many developers, you may find yourself wanting to dig deeper when it comes to a particular bit of code. That's when you'll really appreciate Xcode's Quick Help, header file access, Documentation window, Help menu, and Find tools. With these tools, you can quickly access the documentation for a particular class, method, or property.
To see how this works, say you have the Project window open with the code displayed. What if you want to find out more about UIApplicationDelegate? What, practically speaking, could you do?
Quick Help is an unobtrusive window that provides the documentation for a single symbol - a programming language keyword. It pops up inline, although you can use Quick Help as a symbol inspector (which stays open) by moving the window after it opens. You can also customize the display in Documentation preferences in Xcode preferences.
To get Quick Help for a symbol, double-click to select the symbol in the Text editor and then choose Help → Quick Help. Alternatively right-click and choose Quick Help from the contextual menu that appears.
The header file for a symbol
Headers are a big deal in code because they're the place where you find the class declaration, which includes all of its instance variables and method declarations. To display the header file for a symbol, press Ctrl while doubleclicking the symbol in the Text editor.
The Documentation window lets you browse and search items that are part of the Apple Developer Connection Reference Library (a collection of developer documentation and technical notes) as well as any third-party documentation you have installed.
You access the documentation by pressing Ctrl+Option while double-clicking a symbol. Among other pieces of valuable information, you get access to the Application Programming Interface (API) reference that provides information about the symbol. This access enables you to get the documentation about a method to find out more about it or the methods and properties in a framework class.
Using the Documentation window, you can browse and search the developer documentation - the API references, guides, and article collections about particular tools or technologies - installed on your computer. It's the go-to place for getting documentation about a method or more info about the methods and properties in a framework class.
The Help menu's search field also lets you search Xcode documentation as well as open the Documentation window and Quick Help.
You can also right-click a symbol to display a contextual pop-up menu that gives you similar options to what you see in the Help menu, including Quick Help (and other related functions).
Xcode can also help you find things in your own project. You'll find that, as your classes get bigger, sometimes you'll want to find a single symbol or all occurrences of a symbol in a file or class. You can easily do that by choosing Edit → Find → Find which opens a Find toolbar to help you search the file in the editor window.
You can also use Find to go through your whole project by choosing Edit → Find → Find in Project, which opens the Project Find window. You can type something like view- Controller in the Find field, and then choose In Project, In All Open Files - in the drop-down menu on the right side of the field. (Project Find is a great feature for tracking down something in your code - you're sure to use it often.)
If you select a line in the top pane of the Project Find window, the file in which that instance occurs is opened in the bottom pane and the reference highlighted.
Your searches are saved in your project. Click the triangle next to Find Results in the Groups & Files list to reveal your searches in the Detail view. Select a search to see the search results.
Now that you have some idea of how to use the Xcode Text editor, it's time to write some code.