多肽
/*
多肽：多种形态
1>没有继承就不会有多肽
2>代码体现：父类类型的指针指向子类对象
3>如果函数或者方法中使用的父类类型的参数，那么可以传入父类和子类的对象
4>局限性：
1>>父类类型的变量，不能直接调用子类特有的方法，必须强转成子类的变量类型
*/
main.m
#import <Foundation/Foundation.h>
#import "Animal.h"
#import "Dog.h"
#import "Cat.h"
void eatanimal(Dog *d)
{
[d eat];
}
void eatanimal(Cat *c)
{
[c eat];
}
void eatanimal(Animal *a)
{
[a eat];
}
int main(int argc, const char * argv[])
{
Animal *animal = [Animal new];
Dog *dog = [dog new];
Animal *dog = [Dog new]; // Dog吃东西
Animal *dog = [Animal new]; // Animal吃东西
Animal *dog = [Cat new]; // Cat吃东西
// NSObject *dog = [Dog new]; // 报错 NSObject没有eat方法
[animal eat];
[dog eat];
Cat *cat = [Cat new];
Animal *cat = [Cat new];
[cat run];
Dog *dog = [dog new];
eatanimal(dog);
Cat *cat = [cat new];
eatanimal(cat);
Animal *animal = [animal new];
eatanimal(animal);
[dog test];
// [animal test]; 报错 animal无test方法
// Animal *animal = [Animal new]; 弱语法，Animal中无test方法，需要换成Dog强转
Animal *animal = [Dog new];
Dog *d = (Dog *)animal;
[d test];
return 0;
}
Animal.h
#import <Foundation/Foundation.h>
@interface Animal : NSObject
- (void)eat;
- (void)run;
@end
Animal.m
#import "Animal.h"
@implementation Animal
- (void)eat
{
NSLog(@"Animal——吃东西");
}
- (void)run
{
NSLog(@"Animal——跑起来了");
}
@end
Dog.h
#import "Animal.h"
@interface Dog : Animal
- (void)eat;
- (void)test;
@end
Dog.m
#import "Dog.h"
@implementation Dog
- (void)eat
{
NSLog(@"Dog——吃东西");
}
- (void)test
{
NSLog(@"调用了test方法");
}
@end
Cat.h
#import "Dog.h"
@interface Cat : Dog
@end
Cat.m
#import "Cat.h"
@implementation Cat
- (void)eat
{
NSLog(@"Cat——吃东西");
}
- (void)run
{
NSLog(@"Cat——跑起来了");
}
@end
