[Objective-c 基础 - 2.4] 多态

 1  
 2 #import <Foundation/Foundation.h>
 3 
 4 @interface Animal : NSObject
 5 - (void) eat;
 6 @end
 7 
 8 @interface Dog : Animal
 9 - (void) run;
10 @end
11 
12 @interface Cat : Animal
13 
14 @end
15 
16 
17 @implementation Animal
18 - (void) eat
19 {
20     NSLog(@"吃东西---");
21 }
22 
23 @end
24 
25 @implementation Dog
26 - (void) eat
27 {
28     NSLog(@"狗狗吃东西");
29 }
30 
31 - (void) run
32 {
33     NSLog(@"狗狗跑起来了");
34 }
35 @end
36 
37 @implementation Cat
38 
39 - (void) eat
40 {
41     NSLog(@"猫猫吃东西");
42 }
43 
44 @end
45 
46 void feed(Animal *animal)
47 {
48     NSLog(@"开始喂动物");
49     [animal eat];
50 }
51 
52 
53 int main()
54 {
55     Animal *a = [Dog new];
56     [a eat];
57     Animal *c = [Cat new];
58     [c eat];
59    
60     feed(a);
61     feed(c);
62    
63     Dog *dog = (Dog *)a;
64     [dog run];
65    
66     return 0;
67 }