Using Objective-C Compiler Directives

Objective-C compiler directives begin with @. You often use them to describe portions of a file. In the .h files, for example, @interface marks the beginning of the header interface code. That section is terminated by @end.

In the .m files, @implementation marks the beginning of the implementation, and it is terminated by @end.

Other common Objective-C compiler directives are used to introduce forward declarations such as @class MyClass or @protocol MyProtocol, which are defined in other parts of your code.

Strings in Objective-C are delimited with

@"this is a string"

where the @ alerts the compiler that a string follows.