协议练习

声明一个协议头文件

#ifndef Dog_Play_h
#define Dog_Play_h

@protocol Play <NSObject>
@required
- (void)brak;
- (void)tail;
- (void)go;
@end
#endif

 定一个persons类.

#import <Foundation/Foundation.h>
#import "Play.h"
@interface Person : NSObject

@property (nonatomic, retain) id<Play> animal;

- (void)palyWithPet;


@end

 

#import "Person.h"

@implementation Person

- (void)palyWithPet;
{
    if(_animal!=nil)
        [_animal  brak];
    [_animal  tail];
    [_animal  go];
}
@end

 定义一个猫类

#import "Cat.h"

@implementation Cat : NSObject 

- (void)brak
{
    NSLog(@"miao......miao");
}

- (void)tail
{
    NSLog(@"the dog is roking tail");
}

- (void)go
{
    NSLog(@"the dog is running");
}


@end

 定义一个狗类

#import "Dog.h"

@implementation Dog
- (void)brak
{
    NSLog(@"wang......wang");
}

- (void)tail
{
    NSLog(@"the dog is roking tail");
}

- (void)go
{
    NSLog(@"the dog is running");
}


@end

 主函数中运行,声明person对象,CAT对象,dog对象.然后让person中的annimal指向cat对象,运行person 实例方法playwithannimal,则方法类会调用协议中的那三个方法

#import "ViewController.h"
#import "Person.h"
#import "Cat.h"
#import "Dog.h"
#import "Play.h"
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    Person * person = [[Person alloc]init];
    Dog * cat =[[Dog alloc]init];
    person.animal = cat;
    [person palyWithPet];
    
  


}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end