So where do you find methods that you need? Apple maintains a class reference for each class in its APIs. The class reference lists all of the methods of a class and basic information on how to use them.
In Xcode, select Help → Documentation and API Reference. This will open Xcode’s documentation browser.
In the search field at the top of the window, enter NSString.
NSString class reference
(You can also access the documentation via Apple’s developer website. To get to the NSString class reference, simply search for “NSString class reference.” The first result returned is usually the ...