协议
只做方法声明。本质是一组方法列表，用来规范接口。应用，适用场景
用对象本身体现客观实体，用类对对象进行描述，通过让类遵守相应协议，根据具体业务逻辑进行对应实现来规范对象对行为。协议的遵守者一定是类本身。按照协议规定的方法执行。
创建，制定协议
//
// PersonProtocol.h
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import <Foundation/Foundation.h>
@protocol PersonProtocol <NSObject>
@required
- (void)eat;
@optional
- (void)work;
- (void)play;
@end
//
// PoliceProtocol.h
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import <Foundation/Foundation.h>
@protocol PoliceProtocol <NSObject>
- (void)catchThief;
@end
//
// ThiefProtocol.h
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import <Foundation/Foundation.h>
@protocol ThiefProtocol <NSObject>
- (void)steal;
@end
遵守
//
// Person.h
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "PersonProtocol.h"
@interface Person : NSObject<PersonProtocol>
@end
//
// Person.m
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import "Person.h"
@implementation Person
- (void)eat {
NSLog(@"eat");
}
@end
//
// Police.h
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import "Person.h"
#import "PoliceProtocol.h"
@interface Police : Person<PoliceProtocol>
@end
//
// Police.m
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import "Police.h"
@implementation Police
- (void)eat {
NSLog(@"eat");
}
- (void)work {
NSLog(@"抓小偷");
}
- (void)catchThief {
[self work];
}
@end
//
// Thief.h
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import "Person.h"
#import "ThiefProtocol.h"
@interface Thief : Person<ThiefProtocol>
@end
//
// Thief.m
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import "Thief.h"
@implementation Thief
- (void)steal {
NSLog(@"steal");
}
@end
使用
//
// ViewController.m
// LearnProtocol
//
// Created by 印林泉 on 2017/3/2.
// Copyright © 2017年 yiq. All rights reserved.
//
#import "ViewController.h"
#import "Person.h"
#import "Police.h"
#import "Thief.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
Person *person = [[Person alloc] init];
[person eat];
//[person work];//未实现，调用崩溃
Police *police = [[Police alloc] init];
[police catchThief];
Thief *thief = [[Thief alloc] init];
[thief steal];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
<NSObject>是一个协议，不是类。是父协议。
