ObjectiveC边学边记4：OOP之复合、存取方法

- (id) init // 初始化对象
{if (self &＃61; [super init]) {// 初始化内容}return self;
}


#import /** car3: 添加新的汽车引擎V8 和 轮胎WeatherRadial **/&＃64;interface Engine : NSObject
&＃64;end&＃64;implementation Engine- (NSString *) description
{return (&＃64;"I am a Engine");
}&＃64;end&＃64;interface Tire : NSObject
&＃64;end&＃64;implementation Tire- (NSString *) description
{return(&＃64;"I am a Tire");
}
&＃64;end#pragma mark *** Car ***&＃64;interface Car : NSObject
{Engine *engine;Tire *tires[4];
}
// 添加getter,setter
- (Engine *) engine;
- (void) setEngine:(Engine *) m_engine;- (Tire *) tireAtIndex: (int) index; //通过索引器访问该属性
- (void) setTire: (Tire *) m_tire : (int) index;- (void) print;&＃64;end&＃64;implementation Car//- (id) init // 初始化Car
//{
// if (self &＃61; [super init]) {
// engine &＃61; [Engine new];
//
// tires[0] &＃61; [Tire new];
// tires[1] &＃61; [Tire new];
// tires[2] &＃61; [Tire new];
// tires[3] &＃61; [Tire new];
// }
//
// return self;
//}- (Engine *) engine
{return engine;
}- (void) setEngine:(Engine *)m_engine
{engine &＃61; m_engine;
}- (Tire *) tireAtIndex:(int)index
{if (index <0 || index > 3){NSLog(&＃64;"bad index (%d) in \"tireAtIndex:\"",index);exit(1);}return tires[index];
}- (void) setTire:(Tire *)m_tire :(int)index
{if (index <0 || index >3){NSLog(&＃64;"bad index (%d) in \"setTire:atIndex\"",index);exit(1);}tires[index] &＃61; m_tire;
}
- (void) print
{NSLog(&＃64;"%&＃64;",engine);NSLog(&＃64;"%&＃64;",tires[0]);NSLog(&＃64;"%&＃64;",tires[1]);NSLog(&＃64;"%&＃64;",tires[2]);NSLog(&＃64;"%&＃64;",tires[3]);}// 如果没有重写description方法&＃xff0c;则 %&＃64; 将输出对象的内存地址。
// 如&＃xff1a;
- (NSString *) description
{return &＃64;"I am a Car!";
}&＃64;end// *******************
// V8 Engine Class
&＃64;interface V8 : Engine
&＃64;end&＃64;implementation V8- (NSString *) description
{return &＃64;"I am a V8 Engine!";
}&＃64;end // V8// *******************
// WeatherRadial Tire
&＃64;interface WeatherRadial : Tire
&＃64;end&＃64;implementation WeatherRadial- (NSString *) description
{return (&＃64;"I am a WeatherRadial Tire!!");
}&＃64;endint main (int argc, const char * argv[]) {Car *car;car &＃61; [Car new];V8 *engine &＃61; [V8 new];[car setEngine: engine];int i;for (i &＃61; 0; i <4; i&＃43;&＃43;){WeatherRadial *tire &＃61; [WeatherRadial new];[car setTire:tire :i];}[car print];return 0 ;}