Objective-C Fundamentals

Using Xcode to develop a simple Coin Toss game
7
1.2.2 Expecting an unreliable internet connection
In this age of cloud computing, a number of iOS applications need connectivity to the
internet. The iOS platform provides two main forms of wireless connectivity: local area
in the form of 802.11 Wi-Fi and wide area in the form of various cellular data standards.
These connection choices provide a wide variability in speed, ranging from 300
kilobits to 54 megabits per second. It’s also possible for the connection to disappear
altogether, such as when the user puts the device into flight mode, disables cellular
roaming while overseas, or enters an elevator or tunnel.
Unlike on a desktop, where most developers assume a network connection is
always present, good iOS applications must be designed to cope with network connectivity
being unavailable for long periods of time or unexpectedly disconnecting. The
worst user experience your customers can have is a “sorry, cannot connect to server”
error message while running late to a meeting and needing to access important information
that shouldn’t require a working internet connection to obtain.
In general, it’s important to constantly be aware of the environment in which your
iOS application is running. Your development techniques may be shaped not only by
the memory and processing constraints of the device but also by the way in which the
user interacts with your application.
That’s enough of the background information. Let’s dive right in and create an
iOS application!
1.3 Using Xcode to develop a simple Coin Toss game
Although you might have grand ideas for the next
iTunes App Store smash, let’s start with a relatively simple
application that’s easy to follow without getting
stuck in too many technical details, allowing the unique
features of the development tools to shine through. As
the book progresses, we dig deeper into the finer points
of everything demonstrated. For now the emphasis is on
understanding the general process rather than the specifics
of each technique.
The application you develop here is a simple game
that simulates a coin toss, such as is often used to settle
an argument or decide who gets to go first in a competition.
The user interface is shown in figure 1.2 and consists
of two buttons labeled Heads and Tails. Using these
buttons, the user can request that a new coin toss be
made and call the desired result. The iPhone simulates
the coin toss and updates the screen to indicate if the
user’s choice is correct.
In developing this game, the first tool we need to
investigate is Xcode.
Figure 1.2
game
Coin Toss sample