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。

 1 @implementation SocketComm
 2  
 3 //初始话，创建socket
 4 - (id) init
 5 {
 6     self = [super init];
 7     if (self != nil) {
 8     _sock = [[AsyncSocket alloc] initWithDelegate:self];
 9     [_sock setRunLoopModes:[NSArray arrayWithObject:NSRunLoopCommonModes]];
10 
11 }
12     return self;
13 
14 }

即将连接及发生错误会调用willDisconnectWithError

1 - (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err{
2 
3     [_asyncSocket release];  
4 
5     _asyncSocket = nil;  
6 
7 }

其它方法调用：
1 - (void)onSocketDidDisconnect:(AsyncSocket *)sock;
2 //收到新的socket连接时调用
3 - (void)onSocket:(AsyncSocket *)sock didAcceptNewSocket:(AsyncSocket *)newSocket;
4 
5 - (NSRunLoop *)onSocket:(AsyncSocket *)sock wantsRunLoopForNewSocket:(AsyncSocket *)newSocket;
6 
7 - (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 {
3 
4    [sock readDataWithTimeout:-1 tag:0];  
5 
6 }

   //读取客户端发送来的信息
 1 - (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
 2 {
 3 
 4     NSString *msg = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];
 5 
 6     if(msg)
 7     {
 8 
 9      //处理受到的数据
10 
11     }
12     else
13     {
14 
15        NSLog(@"Error converting received data into UTF-8 String");
16 
17     }
18  
19     [sock readDataWithTimeout:-1 tag:0];
20 
21 }

 1 - (void)onSocket:(AsyncSocket *)sock didReadPartialDataOfLength:(NSUInteger)partialLength tag:(long)tag;
 2 
 3 - (void)onSocket:(AsyncSocket *)sock didWriteDataWithTag:(long)tag;
 4 
 5 - (void)onSocket:(AsyncSocket *)sock didWritePartialDataOfLength:(NSUInteger)partialLength tag:(long)tag;
 6 
 7 - (NSTimeInterval)onSocket:(AsyncSocket *)sock shouldTimeoutReadWithTag:(long)tag 
      elapsed:(NSTimeInterval)elapsed
 8 
 9    bytesDone:(NSUInteger)length;
10 
11 - (NSTimeInterval)onSocket:(AsyncSocket *)sock shouldTimeoutWriteWithTag:(long)tag 
      elapsed:(NSTimeInterval)elapsed
12    bytesDone:(NSUInteger)length; 
13 
14 - (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。