The first application shows how you can put a black-colored window on the iPhone’s screen, allow for the user to press a button, and then display some text in response to the pressing of that button.
The second application is more fun! You use the knowledge gained from your first application to build a simple calculator that does operations with fractions. You can use your
Fraction class that you worked with earlier in the book, as well as a modified
Calculator class. This time, your calculator needs to know how to work with fractions.
Let’s dive right into the first program. This chapter does not cover all the details; as noted, there’s simply not enough space to do that here. Instead, we walk you through ...