iOS中通常的delegate模式只能有一个被委托的对象，这样当需要有多个被委托的对象时，实现起来就略为麻烦，在开源库XMPPFramework中提供了一个GCDMulticastDelegate类，使用它可以为一个对象添加多个被委托的对象，用起来也比较方便

一. 定义一个协议

#import <Foundation/Foundation.h>

@protocol MulticastDelegateBaseObjectDelegate <NSObject>

- (void)testDelegate;

@end

二. 创建多播对象

        multicastDelegate = (GCDMulticastDelegate <MulticastDelegateBaseObjectDelegate>*)[[GCDMulticastDelegate alloc] init];

三. 创建一个类实现协议里的方法

#import "CustomLabel.h"

@implementation CustomLabel


#pragma mark - <MulticastDelegateBaseObjectDelegate>

- (void)testDelegate {
    NSLog(@"－－－－－多播");
}

@end

五. 添加代理到多播中

[multicastDelegate addDelegate:lable delegateQueue:dispatch_get_main_queue()];

四. 创建一个方法调用协议方法

- (void)test1 {
    NSLog(@"test1----");
    [multicastDelegate testDelegate];
//    [multicastDelegate testDelegate];
}

五. 调用test1

  [userInfo test1];

核心

MulticastDelegateBaseObject.h

#import <Foundation/Foundation.h>
#import "GCDMulticastDelegate.h"

#import "MulticastDelegateBaseObjectDelegate.h"//协议

//多播委托的基类
@interface MulticastDelegateBaseObject : NSObject{
    id multicastDelegate;
    dispatch_queue_t moduleQueue;
    void *moduleQueueTag;
}

- (id)init;
- (id)initWithDispatchQueue:(dispatch_queue_t)queue;

@property (readonly) dispatch_queue_t moduleQueue;
@property (readonly) void *moduleQueueTag;

- (void)addDelegate:(id)delegate delegateQueue:(dispatch_queue_t)delegateQueue;
- (void)removeDelegate:(id)delegate delegateQueue:(dispatch_queue_t)delegateQueue;
- (void)removeDelegate:(id)delegate;

//调用test1,会使注册了的对象都执行 testDelegate 方法
- (void)test1;

@end

MulticastDelegateBaseObject.m

#import "MulticastDelegateBaseObject.h"

@implementation MulticastDelegateBaseObject

- (id)init
{
    return [self initWithDispatchQueue:NULL];
}

- (id)initWithDispatchQueue:(dispatch_queue_t)queue
{
    if ((self = [super init]))
    {
        if (queue)
        {
            moduleQueue = queue;
        }
        else
        {
            const char *moduleQueueName = [NSStringFromClass([self class]) UTF8String];
            moduleQueue = dispatch_queue_create(moduleQueueName, NULL);
        }
        
        moduleQueueTag = &moduleQueueTag;
        dispatch_queue_set_specific(moduleQueue, moduleQueueTag, moduleQueueTag, NULL);
        
        //协议
        multicastDelegate = (GCDMulticastDelegate <MulticastDelegateBaseObjectDelegate>*)[[GCDMulticastDelegate alloc] init];
    }
    return self;
}

//------------------

- (void)test1 {
    NSLog(@"test1----");
    [multicastDelegate testDelegate];
//    [multicastDelegate testDelegate];
}

//------------------

- (dispatch_queue_t)moduleQueue
{
    return moduleQueue;
}

- (void *)moduleQueueTag
{
    return moduleQueueTag;
}

- (void)addDelegate:(id)delegate delegateQueue:(dispatch_queue_t)delegateQueue
{
    dispatch_block_t block = ^{
        [multicastDelegate addDelegate:delegate delegateQueue:delegateQueue];
    };
    
    if (dispatch_get_specific(moduleQueueTag))
        block();
    else
        dispatch_async(moduleQueue, block);
}

- (void)removeDelegate:(id)delegate delegateQueue:(dispatch_queue_t)delegateQueue synchronously:(BOOL)synchronously
{
    dispatch_block_t block = ^{
        [multicastDelegate removeDelegate:delegate delegateQueue:delegateQueue];
    };
    
    if (dispatch_get_specific(moduleQueueTag))
        block();
    else if (synchronously)
        dispatch_sync(moduleQueue, block);
    else
        dispatch_async(moduleQueue, block);
    
}
- (void)removeDelegate:(id)delegate delegateQueue:(dispatch_queue_t)delegateQueue
{
    [self removeDelegate:delegate delegateQueue:delegateQueue synchronously:YES];
}

- (void)removeDelegate:(id)delegate
{
    [self removeDelegate:delegate delegateQueue:NULL synchronously:YES];
}

@end

MulticastDelegateBaseObjectDelegate.h

#import <Foundation/Foundation.h>

@protocol MulticastDelegateBaseObjectDelegate <NSObject>

- (void)testDelegate;

@end

demo链接:https://pan.baidu.com/s/1czctNg