stl

In the Java programming language there are both raw and wrapper objects to represent numbers. For example, int and Integer, double and Double, etc. If one wanted to add a numeric object to a Collection object, it required using the wrapper object rather than the raw type.

With the introduction of autoboxing in Java 1.5, moving between these types would largely be handled by the compiler, but there is still a distinction.

Just as with null types, Objective-C also requires that you wrap raw types before inserting them into objects or using them in variable argument lists where the type id is expected. To help us with this, cocoa provides NSNumber.

One of the really powerful libraries available to C++ programmers is the Standard Template Library (STL). While Cocoa has fantastic built-in classes, sometimes it is beneficial--especially when working with algorithms where raw numbers are being used and speed is more important--to use the STL.

Using the STL in Objective-C requires that you switch the file to use Objective-C++ by changing the file ending to .mm. After that you can import the various STL libraries normally: #import <vector>.

See Also:

• Standard Template Library Programmer's Guide
  
• The Objective-C 2.0 Programming Language: Using C++ With Objective-C