Investigate the lowercase and uppercase methods of NSString using the debugger.

Write a Foundation Tool command-line application that prints the contents of any filename given to it.

Read the documentation on your hard drive about the NSArray, NSSet, and NSDictionary classes.

Modify the arrays example application so that it saves the contents of the array to a file.

Write an example that saves a dictionary to disk. Don't just use string objects in the array, but use some other objects like dictionaries and numbers so that you can see how Cocoa saves different types out to XML property lists.

Examine the code we've written so far with an eye for how memory is managed. (A bug regarding memory management has been left in one of the examples.)