Objective-C Fundamentals

Looping statements
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Not as straightforward is the Kitten case, which doesn’t end in a break statement.
If the switch statement is executed while the pet variable stores the value Kitten, the
first call to NSLog is executed, and execution proceeds to the next statement. Because
the Kitten case has no additional statements, execution “falls through” into the Cat
case block, and the second call to NSLog is executed.
It’s not necessary for a case block to have any statements, as in Horse case: notice it
immediately falls through into the case for Pony. This feature is handy when multiple
values should be treated identically.
With your newfound knowledge of conditional statements, you can alter the
sequence of operations your applications perform. And the C developer’s toolbox has
even more tricks. As in real life, the path an iPhone application executes is not
straight; it can contain many twists and turns. You may want to repeat a set of statements
or continue doing something until a certain condition becomes true, such as a
user pressing a button or an array running out of data. Looping statements with keywords
such as for and while are a natural progression from conditional statements
and enable an application to repeat a set of statements.
B.4 Looping statements
In your application logic you may come across the need to repeat a particular statement
a fixed number of times. In chapter 1 you printed "Hello, World!" to the
debug console with the following statement:
NSLog(@"Hello, World!");
If you wanted to say "Hello, World!" three times in a row, you might be tempted to
add two calls to NSLog:
NSLog(@"Hello, World!");
NSLog(@"Hello, World!");
NSLog(@"Hello, World!");
Using an if statement, it’s possible to extend this approach to make the number of
times you print "Hello, World!" conditional on the value stored in a variable. For
example, the code in the following listing uses the value of variable n to determine
how many times to print "Hello, World!" to the console (between 0 and 3 times).
Listing B.5
Controlling how many times a message is logged based on program state
int n = 2;
if (n > 0)
NSLog(@"Hello, World!");
if (n > 1)
NSLog(@"Hello, World!");
if (n > 2)
NSLog(@"Hello, World!");
While this technique is perfectly acceptable, it may not be the best or most scalable
approach. As an example, try to extend this technique to print "Hello, World!"