IOS使用AsyncSocket进行Socket通信

首先导入CFNetwork.framework框架

1、下载ASyncSocket库源码
 
2、把ASyncSocket库源码加入项目
 
3、在项目增加CFNetwork框架

使用AsyncSocket开源的框架可以很方便的与其它系统进行Socket通信， AsyncSocket包括TCP和UDP，

通过实现委托AsyncSocketDelegate进行交互。AsyncSocketDelegate有如下消息调用。

 @implementation SocketComm

 //初始话，创建socket

 - (id) init

 {

     self = [super init];

     if (self != nil) {

     _sock = [[AsyncSocket alloc] initWithDelegate:self];

     [_sock setRunLoopModes:[NSArray arrayWithObject:NSRunLoopCommonModes]];

 }

     return self;

 }

即将连接及发生错误会调用willDisconnectWithError

 - (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err{

     [_asyncSocket release];

     _asyncSocket = nil;

 }

其它方法调用：
1 - (void)onSocketDidDisconnect:(AsyncSocket *)sock;

 //收到新的socket连接时调用

 - (void)onSocket:(AsyncSocket *)sock didAcceptNewSocket:(AsyncSocket *)newSocket;

 - (NSRunLoop *)onSocket:(AsyncSocket *)sock wantsRunLoopForNewSocket:(AsyncSocket *)newSocket;

 - (BOOL)onSocketWillConnect:(AsyncSocket *)sock;

网络连接成功后,调用didConnectToHost, 收发数据中必须添加 [sock readDataWithTimeout:-1 tag:0];否则接收不到数据，

并且这个函数在数据返回就必须调用一次，让他一直循环下去

//异步返回的连接成功
1 - (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port
2 {

    [sock readDataWithTimeout:- tag:];

 }

   //读取客户端发送来的信息
 1 - (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag

 {

     NSString *msg = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];

     if(msg)

     {

      //处理受到的数据

     }

     else

     {

        NSLog(@"Error converting received data into UTF-8 String");

     }

     [sock readDataWithTimeout:- tag:];

 }

 - (void)onSocket:(AsyncSocket *)sock didReadPartialDataOfLength:(NSUInteger)partialLength tag:(long)tag;

 - (void)onSocket:(AsyncSocket *)sock didWriteDataWithTag:(long)tag;

 - (void)onSocket:(AsyncSocket *)sock didWritePartialDataOfLength:(NSUInteger)partialLength tag:(long)tag;

 - (NSTimeInterval)onSocket:(AsyncSocket *)sock shouldTimeoutReadWithTag:(long)tag 
      elapsed:(NSTimeInterval)elapsed

    bytesDone:(NSUInteger)length;

 - (NSTimeInterval)onSocket:(AsyncSocket *)sock shouldTimeoutWriteWithTag:(long)tag 
      elapsed:(NSTimeInterval)elapsed

    bytesDone:(NSUInteger)length;

 - (void)onSocketDidSecure:(AsyncSocket *)sock;

AsyncSocket包括connectToHost，writeData，readDataWithTimeout等基本调用，发送这些消息，会触发相应Delegate相应的方法。