Graphics Programs Reference
In-Depth Information
plication. Select Debug RandomPossessions at the top of the log navigator to see your
console output in the editor area ( Figure 2.6 ).
Figure 2.6 Console output
Now let's go back and take a closer look at the code in your main function.
Creating strings
First, notice the @"One" argument in the first addObject: message sent to items .
[items addObject:@"One"];
In Objective-C, when you want a hard-coded string, you prefix a character string with an
@ symbol. This creates an instance of NSString that holds the character string.
But, wait - aren't instances created by sending alloc to a class? Yes, but the @ prefix is
a special case just for the NSString class. It is convenient shorthand for creating strings.
The following code shows three such uses, and each is completely valid Objective-C,
where length is a message you can send to an instance of NSString :
NSString *myString = @"Hello, World!";
int len = [myString length];
len = [@"Hello, World!" length];
myString = [[NSString alloc] initWithString:@"Hello, World!"];
len = [myString length];
Format strings
Next, let's look at the NSLog function we used to print to the console. NSLog takes a
variable number of arguments and prints a string to the console. The first argument is re-
quired and must be an NSString instance. This instance is called the format string , and
 
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