main:

1 #import 
     
       2 #import "Animal.h"         3 #import "Fish.h" 4 #import "Bird.h" 5  6 void doAction(Animal *ani) 7 { 8     [ani action];       //用父类参数ani，调用父类中的action 9 }10 11 int main(int argc, const char * argv[]) {12     @autoreleasepool {13         Animal *animal=[[Animal alloc]init];14         Bird *bird=[[Bird alloc]init];15         Fish *fish=[[Fish alloc]init];16         17         doAction(animal);           //传入父类实例animal18         doAction(bird);             //传入子类实例bird19         doAction(fish);             //传入子类实例fish20     }21     return 0;22 }
     

Animal.h:

1 #import 
     
      2 3 @interface Animal : NSObject4 -(void)action;5 @end
     

Animal.m:

1 #import "Animal.h"2 3 @implementation Animal4 -(void)action{5     NSLog(@"Animal Moving~");6 }7 @end

Fish.h:

1 #import "Animal.h"2 3 @interface Fish : Animal4 -(void)action;5 @end

Fish.m:

1 #import "Fish.h"2 3 @implementation Fish4 -(void)action{5     NSLog(@"Fish Swiming~");6 }7 @end

Bird.h:

#import "Animal.h"@interface Bird : Animal-(void)action;@end

Bird.m:

1 #import "Bird.h"2 3 @implementation Bird4 -(void)action{5     NSLog(@"Bird Flying~");6 }7 @end