Protocol and Class

APerfactDelegate.h

//
//  APerfactDelegate.h
//  ReactiveCocoaPractice
//
//  Created by mengqian on 20/9/2016.
//  Copyright © 2016 thinktube. All rights reserved.
//

#ifndef APerfactDelegate_h
#define APerfactDelegate_h

@protocol APerfectDelegate <NSObject>

@property(nonatomic, readonly)NSString *name;
@property(nonatomic, readonly)NSNumber *count;

@optional
- (void)optionalSel;

@required
- (void)requriedSel;

@end


#endif /* APerfactDelegate_h */

ExamViewController.m

#import "ExamViewController.h"
#import "Perfact.h"
#import "MyClass.h"

@interface ExamViewController ()<APerfectDelegate>
@end

@implementation ExamViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor whiteColor];
    Perface *per = [[Perface alloc] init];
    per.delegate = self;
    [per actionWithMethodName:nil];
    
    MyClass *cls = [[MyClass alloc]init];
    NSLog(@"MyClass's name: %@",cls.name);
    [cls methodA];
}

-(void)optionalSel
{
    NSLog(@"ExamViewController optionalSel");
}

@end

gistfile1.txt

MyClass.h

//
//  ProtocolInherits.h
//  ReactiveCocoaPractice
//
//  Created by mengqian on 21/9/2016.
//  Copyright © 2016 thinktube. All rights reserved.
//
@protocol A
@property (nonatomic, readonly) NSString* name;

@required
-(void) methodA;

@end

// B 协议继承自 A,协议也可以多重继承, 比如 <A, NSObject>
@protocol B <A>
@required
-(void) methodB;
@end

// ===================================
@interface MyClass : NSObject <B>
// 协议可以被实例实现, 也可以赋值给变量使用
@property(nonatomic, weak) id <B> delegate;
@end

@implementation MyClass
@synthesize delegate;
@synthesize name; // A的name属性也是可以直接用

-(instancetype)init
{
    self = [super init];
    if(self){
        [delegate methodB]; // 可以调用B的方法
        [delegate methodA]; // 可以调用B继承的A的方法
        // 这里这两个方法不会执行, 因为delegate的宿主并不是这个类. 除非self.delegate = self;
        // 那么会走下面的两个方法 methodB methodA. delegate指向谁,谁负责实现
    }
    return self;
}
-(void)methodB  // 必须要实现
{
}
-(NSString *)name{
    return @"MyClass";
}
-(void)methodA // 必须要实现
{
    NSLog(@"methodA: %@",self.name);
}
@end

Perfact.h

//
//  Perface.h
//  ReactiveCocoaPractice
//
//  Created by mengqian on 20/9/2016.
//  Copyright © 2016 thinktube. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "APerfactDelegate.h"
@interface Perfact : NSObject<APerfectDelegate>

@property(nonatomic, assign) id<APerfectDelegate> delegate;

-(void)actionWithMethodName:(NSString*)methodName;


@end

Perfact.m

//
//  Perface.m
//  ReactiveCocoaPractice
//
//  Created by mengqian on 20/9/2016.
//  Copyright © 2016 thinktube. All rights reserved.
//

#import "Perface.h"

@implementation Perfact

@synthesize delegate;

- (instancetype)init
{
    self = [super init];
    if (self) {
        // Initialize self.
        // 需要给delegate对象指定宿主,要不无法去寻找具体的实现方法
        //self.delegate = self;
        
        if(delegate != nil && [delegate respondsToSelector:@selector(optionalSel)]){
            [delegate optionalSel];
        }
    }
    return self;
}

- (void)optionalSel
{
    NSLog(@"optionalSel %@",self.name);
}

- (void)requriedSel
{
    NSLog(@"requriedSel");
}

-(void)actionWithMethodName:(NSString*)methodName;
{
    // 默认方法
    if(delegate != nil && [delegate respondsToSelector:@selector(optionalSel)]){
        [delegate optionalSel];
    }
    //通过methodName 去反射方法
}

@end