[Objective-C basic tutorial note ch05] (6) Composition in oC

1. composite is implemented by including object pointers as instance variables.

@ Interface unicycle: nsobject

{

Pedal * pedal;

Tire * tire;

} // The pedal and tire composite the unicycle

2. Access Method-a method used to read or change the attributes of an object.

# Import <Foundation/Foundation. h>

@ Interface car: nsobject

{

Engine * engine;

Tire * tires [4];

}

-(Engine *) engine; // getter setter

-(Void) setengine: (engine *) newengine; // setter

-(Tire *) tireatindex: (INT) index;

-(Void) settire: (tire *) tire atindex: (INT) index;

@ End // car

3. Inheritance and combination

Inheritance is the "is a" link; combination is the "has a" link.