Objective-C Programming: The Big Nerd Ranch Guide

C primitive types

The collections covered in this chapter only hold objects. What if you want a collection of floats or ints? You can wrap common C number types using NSNumber.

You can create a literal NSNumber instance using the @ symbol – similar to how you create literal NSString instances. For instance, if you wanted to put the numbers 4 and 5.6 into an array, you would create the instance of NSNumber and then add the NSNumber object to the array:

N​S​M​u​t​a​b​l​e​A​r​r​a​y​ ​*​l​i​s​t​ ​=​ ​[​[​N​S​M​u​t​a​b​l​e​A​r​r​a​y​ ​a​l​l​o​c​]​ ​i​n​i​t​]​;​
[​l​i​s​t​ ​a​d​d​O​b​j​e​c​t​:​@​4​]​;​
[​l​i​s​t​ ​a​d​d​O​b​j​e​c​t​:​@​5​.​6​]​;​

Note that you cannot do math directly with an NSNumber, only with primitives. You must ...