20150617_OC之父类指针指向子类对象

最新推荐文章于 2023-05-09 18:54:39 发布

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#父类指针 #子类变量

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本文详细介绍了Objective-C中使用父类指针指向子类对象实现多态的方法，通过定义Animal类及其子类Cat和Dog，展示了如何通过方法重写和多态特性来打印不同动物的特定行为和属性。

//
//  Animal.h
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Animal : NSObject
{
    NSString    *_name;
    NSInteger    _age;
}

@property (copy,nonatomic)NSString *name;
@property (assign ,nonatomic)NSInteger age;

- (void)printAnimalFood;
@end

<pre name="code" class="objc">//  Animal.m
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import "Animal.h"

@implementation Animal

- (void)printAnimalFood
{
    
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"name = %@,age = %li",[self name],[self age]];
}

@end

//  Cat.h
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import "Animal.h"

@interface Cat : Animal
{
    NSString *_colorOfCat;
}
@property (copy,nonatomic)NSString *colorOfCat;
@end

//  Cat.m
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import "Cat.h"

@implementation Cat
- (void)printAnimalFood
{
    NSLog(@"Cat like to eat fish");
}

- (NSString *)description
{
    return  [NSString stringWithFormat:@"name = %@,age = %li,color = %@",_name,_age,self->_colorOfCat];
}
@end

//  Dog.h
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import "Animal.h"

@interface Dog : Animal
{
    float _weight;
}
@property (assign,nonatomic)float weight;
@end

<pre name="code" class="objc">//
//  Dog.m
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import "Dog.h"

@implementation Dog

- (void)printAnimalFood
{
    NSLog(@"Dog like to eat bone");
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"name = %@,age = %li,weight = %.2f",_name,_age,_weight];
}
@end

<pre name="code" class="objc">//  main.m
//  IOS150617_ObjectiveC_父类指针指向子类对象
//
//  Created by qianfeng on 15/6/17.
//  Copyright (c) 2015年 Peng Junlong. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Cat.h"
#import "Dog.h"

//多态,父类指针指向子类对象,
void printInfo(Animal *animal)
{
    [animal printAnimalFood];
    NSLog(@"%@",animal.description);
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Dog *dog = [[Dog alloc]init];
        dog.name = @"狗";
        dog.age  = 12;
        dog.weight = 12.34;
        [dog printAnimalFood];
        NSLog(@"%@",dog.description);
        
        //父类的对象指针指向子类的对象
        //调用的方法看具体对象的类型,先从子类查找对应方法的实现,子类没有实现对应的方法,跳到父类查找对应的方法实现,父类没有实现对应的方法,再继续向上追踪到父类的父类
        Animal *dogAnimal = dog;
        [dogAnimal printAnimalFood];
        NSLog(@"%@",dogAnimal.description);
    
        Cat *cat = [[Cat alloc] init];
        cat.name = @"猫";
        cat.age  = 10;
        cat.colorOfCat = @"白色";
        [cat printAnimalFood];
        NSLog(@"%@",[cat description]);
        
        Animal *catAnimal = cat;
        [catAnimal printAnimalFood];
        NSLog(@"%@",catAnimal.description);
        
        NSLog(@"==========多态=========");
        //多态,根据不同的对象,打印不同的结果
        printInfo(cat);
        printInfo(dog);
    }
    return 0;
}