When I'm typing up a Cocoa object and calling a selector on that object, I sometimes can see 'documentation' or 'help' information about that method. For instance, as I type [NSArray alloc], I see two help hints. One for NSArray, and one for alloc. Both of these appear in the popup autocomplete suggestions listbox as I type the code.
How do I produce similar method/class decorated help hints which will appear when I type? I want to see my comments as I type my custom class name and custom methods. How can I do this?
For instance, C# provides this feature through XML documentation which can be placed before any method, class, or interface/protocol declaration.
You have to create a “docset”. There are tools like appledoc for creating docsets from your comments. You could set up a build phase that runs appledoc on your code.
The problem is that there's no way to make Xcode 4 reload a docset except by restarting Xcode. So even if you run appledoc automatically as part of your build, you will have to restart Xcode to make it see the changes to your docset.
来源：https://stackoverflow.com/questions/12417435/how-to-decorate-objective-c-methods-with-documentation