汽车继承自车辆

考虑一个基类 Vehicle 及其派生类 Car 如下：

#import <Foundation/Foundation.h>
 
@interface Vehicle : NSObject

{
    NSString *vehicleName;
    NSInteger vehicleModelNo;
}

- (id)initWithName:(NSString *)name andModel:(NSInteger)modelno;
- (void)print;
@end

@implementation Vehicle

- (id)initWithName:(NSString *)name andModel:(NSInteger)modelno{
    vehicleName = name;
    vehicleModelNo = modelno;
    return self;
}

- (void)print{
    NSLog(@"Name: %@", vehicleName);
    NSLog(@"Model: %ld", vehicleModelNo);
}

@end

@interface Car : Vehicle

{
    NSString *carCompanyName;
}

- (id)initWithName:(NSString *)name andModel:(NSInteger)modelno 
  andCompanyName:(NSString *)companyname;
- (void)print;

@end

@implementation Car

- (id)initWithName:(NSString *)name andModel:(NSInteger) modelno 
  andCompanyName: (NSString *) companyname
  {
    vehicleName = name;
    vehicleModelNo = modelno;
    carCompanyName = companyname;
    return self;
}
- (void)print
{
    NSLog(@"Name: %@", vehicleName);
    NSLog(@"Model: %ld", vehicleModelNo);
    NSLog(@"Company: %@", carCompanyName);
}

@end

int main(int argc, const char * argv[])
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];        
    NSLog(@"Base class Vehicle Object");
    Vehicle *vehicle = [[Vehicle alloc]initWithName:@"4Wheeler" andModel:1234];
    [vehicle print];
    NSLog(@"Inherited Class Car Object");
    Car *car = [[Car alloc]initWithName:@"S-Class" 
    andModel:7777 andCompanyName:@"Benz"];
    [car print];        
    [pool drain];
    return 0;
}

编译并执行上述代码时，会产生以下结果：

2016-09-29 18：21：03.561 继承[349：303]基类车辆对象

2016-09-29 18：21：03.563 继承[349：303]姓名：4Wheeler

2016-09-29 18：21：03.563 继承[349：303]型号：1234

2016-09-29 18：21：03.564 Inheritance [349：303]继承的 Class Car 对象

2016-09-29 18：21：03.564 继承[349：303]名称：S 级

2016-09-29 18：21：03.565 继承[349：303]型号：7777

2016-09-29 18：21：03.565 继承[349：303]公司：奔驰