iOS UDP 广播

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感谢作者: 清澈Saup


1.前言  

   什么是UDP协议广播机制?      举一个例, 例如在一群人群中,一个人要找张三,于是你向人群里大喊一声(广播):“谁是张三”   如果它是张三,它就会回应你,在网络中也是一样的。        UDP广播机制的应用场景:       若干个客户端,在局域网内(不知道IP的情况下) 需要在很多设备里需找特有的设备,比如服务器,抑或是某个打印机,传真机等。          假设我现在准备将服务器装在永不断电的iPad上。     若干个客户端iPhone 一激活,就要来向所有设备广播,谁是服务器,是服务器的话,请把IP地址告诉我。然后我就去连接,然后进入长连接,后台接受消息。

2.UDP广播机制的实现  

注:  iPad:服务器端  iPhone:客户端  

2.1.服务器端(iPad)的实现  

2.1.1.先去github上下载 AsyncUdpSocket.h框架包  

2.1.2.初始化udp  

@interface QCViewController (){ AsyncUdpSocket *asyncUdpSocket;}      asyncUdpSocket = [[AsyncUdpSocket alloc] initWithDelegate:self];

2.1.3.绑定端口  

   NSError *err = nil;    [asyncUdpSocket enableBroadcast:YES error:&err];    [asyncUdpSocket bindToPort:9527 error:&err];   //启动接收线程    [asyncUdpSocket receiveWithTimeout:-1 tag:0];

 2.1.4.实现代理方法  

//已接收到消息- (BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port{    if(data是找服务器的){              //根据客户端给的IP,利用TCP或UDP 相互连接上就可以开始通讯了      }  return YES;}//没有接受到消息-(void)onUdpSocket:(AsyncUdpSocket *)sock didNotReceiveDataWithTag:(long)tag dueToError:(NSError *)error{}//没有发送出消息-(void)onUdpSocket:(AsyncUdpSocket *)sock didNotSendDataWithTag:(long)tag dueToError:(NSError *)error{ }//已发送出消息-(void)onUdpSocket:(AsyncUdpSocket *)sock didSendDataWithTag:(long)tag{}//断开连接-(void)onUdpSocketDidClose:(AsyncUdpSocket *)sock{}

2.2.客户端(iPhone)的实现  

注:实现步骤与服务器端相似

2.2.1.初始化udp   

@interface QCViewController (){ AsyncUdpSocket *asyncUdpSocket;}      asyncUdpSocket = [[AsyncUdpSocket alloc] initWithDelegate:self];

2.2.2.绑定端口    

   NSError *err = nil;    [asyncUdpSocket enableBroadcast:YES error:&err];    [asyncUdpSocket bindToPort:9527 error:&err];

2.2.3.实现代理方法  

//已接收到消息- (BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port{ return YES;}//没有接受到消息-(void)onUdpSocket:(AsyncUdpSocket *)sock didNotReceiveDataWithTag:(long)tag dueToError:(NSError *)error{}//没有发送出消息-(void)onUdpSocket:(AsyncUdpSocket *)sock didNotSendDataWithTag:(long)tag dueToError:(NSError *)error{ }//已发送出消息-(void)onUdpSocket:(AsyncUdpSocket *)sock didSendDataWithTag:(long)tag{}//断开连接-(void)onUdpSocketDidClose:(AsyncUdpSocket *)sock{}

2.2.4.广播寻找  

注:广播iP地址为 255.255.255.255

       NSString *str = @'谁是服务器?我的IP是:192.168.80.103';       NSData *data=[str dataUsingEncoding:NSUTF8StringEncoding];       [asyncUdpSocket sendData:data                          toHost:@'255.255.255.255                            port:9527                     withTimeout:-1                               tag:0]; 


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