[Object-C] @ Class

In objective-C, when a class needs to reference another class, that is, to establish a composite relationship, you need to create a pointer to the referenced class in the Class header file. For example: car. h # import @ interface car: nsobject {tire * tires [4]; engine * engine ;}... The implementation class is omitted first. If you compile it like this, the compiler will report an error, telling you that it does not know what tire and engine are. At this time, there are two options: one is the import header file of the two referenced classes, and the other is to declare tire and engine as class names using @ class. The difference between the two is that import will contain all information about this class, including entity variables and methods, while @ class only tells the compiler that the name declared after it is the name of the class, as for how these classes are defined, you do not need to consider them for the moment. I will tell you later. In header files, you only need to know the name of the referenced class. You do not need to know its internal entity variables and methods. Therefore, in header files, @ class is generally used to declare this name as the class name. In the implementation class, because the internal object variables and methods of the referenced class are used, # import must be used to include the header file of the referenced class.

To:Http://blog.sina.com.cn/s/blog_69081e060100p4r1.html