Question

When creating a new outlet in Xcode 4 it enters the necessary code like usual, but it prefixes a _ in the header file interface (but not in the properties):

UINavigationController *_mainNavController;
UIViewController *_rootView;

it also does this in the implementation file:

@synthesize mainNavController = _mainNavController;
@synthesize rootView = _rootView;

While I can of course use them with the prefixed _, it just makes my code messy. Am I doing something horribly wrong?

Many thanks in advance.

Answer 1

I can of course use them with the
prefixed _.

Why don’t you use your properties (like self.mainNavController) instead of the backing ivars directly?

Read what Apple has to say about using accessor methods:

Sometimes it might seem tedious or
pedantic, but if you use accessor
methods consistently the chances of
having problems with memory management
decrease considerably. If you are
using retain and release on instance
variables throughout your code, you
are almost certainly doing the wrong
thing.

Properties encapsulate memory management code and thus reduce boilerplate.

The only places you shouldn’t use
accessor methods to set an instance
variable are in init methods and
dealloc.

Also, the convention of prefixing backing ivars with _ prevents you from accessing the backing ivars directly by mistake (and fail to retain an object, for example).