objective-C 多态

//
//  main.m
//  mobile

#import <Foundation/Foundation.h>
#import "Communication.h"
#import "Electrograph.h"
#import "Telephone.h"
#import "Student.h"
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Peerson *p=[[Student alloc]init];
      Communication *cuo=[[Electrograph alloc]init];
        [p sayhi:cuo];
        cuo=[[Communication alloc]init];
        [p sayhi:cuo];
        cuo=[[Telephone alloc]init];
        [p sayhi:cuo];
    }
    return 0;
}

//
//  Peerson.h
//  mobile
#import <Foundation/Foundation.h>
#import "Communication.h"
@interface Peerson : NSObject
-(void)sayhi:(Communication *)say;
@end
//
//  Peerson.m
//  mobile

#import "Peerson.h"

@implementation Peerson
-(void)sayhi:(Communication *)say{
    [say call];
}
@end

//
//  Student.h
//  mobile
#import "Peerson.h"

@interface Student : Peerson

@end

//
//  Student.h
//  mobile


#import "Peerson.h"

@interface Student : Peerson

@end

//
//  Communication.h
//  mobile

#import <Foundation/Foundation.h>

@interface Communication : NSObject
-(void)call;
@end

//
//  Communication.m
//  mobile

#import "Communication.h"

@implementation Communication
-(void)call{
    NSLog(@"我正在打电话呢");
}
@end

//
//  Electrograph.h
//  mobile

#import "Communication.h"

@interface Electrograph : Communication

@end

//
//  Electrograph.m
//  mobile
#import "Electrograph.h"

@implementation Electrograph
-(void)call{
    NSLog(@"我正在和就家人打电话");
}
@end

//
//  Telephone.h
//  mobile
#import "Communication.h"

@interface Telephone : Communication

@end

//
//  Telephone.m
//  mobile

#import "Telephone.h"

@implementation Telephone
-(void)call{
    NSLog(@"我的手机能上网");
}
@end