OC language--recombination and inheritance

1. Composite

1.0 Compounding and inheritance

-"describes the relationship between a class and a class or object and an object in two ways: 1. Inheritance 2. Compound;

-"Inheritance can define a new class with all the functions of the parent class.

-"composite, the object can refer to other objects.

Difference:

-"Compound: has-a Car has a tire (inclusive relationship)

-"Inherited: Is-a A Male is a person (affiliation)

1. 1 Basic syntax examples for compositing

#import "Tire.h" #import "Engine.h" @interface car:nsobject{    //Save the address of the tyre and engine    *_engine;    Tire *_tires[4];} -(Car *) init;-(void) run;-(void) Setengine: (Engine *) newengine;-(engine *) engine; @end

2. Use of @class keywords

2. 1 Basic concepts and basic grammar

-"@class The role of the keyword: declaring a pre-reference to a class

-"Grammar writing: @class class name;

Note: When class A needs to use the class name of Class B,

We can use @class to declare this class B;

Use @class B in the A.h file of Class A;

In the a.m., use #import "B.h" to import the header file of Class B.

2. The difference between the 2 @class and the #import

1. @class is merely a declaration of a single class, equivalent to an extern statement;
2. #import is to import the entire header file, equivalent to # include

OC language--recombination and inheritance