导入AsynSocket库，导入CFNetwork系统库

1.新建single view工程

ViewController.h文件

    #import <UIKit/UIKit.h>        #import "AsyncSocket.h"                @interface ViewController : UIViewController <AsyncSocketDelegate> {            NSMutableArray *_socketArray;            AsyncSocket *_sendSocket;//发送            AsyncSocket *_recvSocket;//接收        }        - (IBAction)sendClick:(id)sender;        @property (retain, nonatomic) IBOutlet UITextField *ipField;        @property (retain, nonatomic) IBOutlet UITextField *sendField;        @property (retain, nonatomic) IBOutlet UITextView *msgView;        - (IBAction)conClick:(id)sender;        - (IBAction)sendClick:(id)sender;        @end  

2.ViewController.m文件

    #import "ViewController.h"                @implementation ViewController        @synthesize ipField;        @synthesize sendField;        @synthesize msgView;                - (void)viewDidLoad        {            [super viewDidLoad];                        //初始化socket数组，存放socket            _socketArray = [[NSMutableArray alloc] init];                        //实例化客户端和服务器socket            _sendSocket = [[AsyncSocket alloc] initWithDelegate:self];            _recvSocket = [[AsyncSocket alloc] initWithDelegate:self];                        //服务器段开始监听            [_recvSocket acceptOnPort:5566 error:nil];        }                //服务器端接收到新的socket        - (void)onSocket:(AsyncSocket *)sock didAcceptNewSocket:(AsyncSocket *)newSocket {            //服务器端将收到的socket存入数组            [_socketArray addObject:newSocket];            //开始接收数据            [newSocket readDataWithTimeout:-1 tag:0];        }                //服务器端接收到信息        - (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag {            NSString *string = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];            self.msgView.text = [NSString stringWithFormat:@"%@%@:%@\n", self.msgView.text, sock.connectedHost, string];            [sock readDataWithTimeout:-1 tag:0];//循环        }                //连接        - (IBAction)conClick:(id)sender {            if (_sendSocket.isConnected) {                [_sendSocket disconnect];            }            [_sendSocket connectToHost:self.ipField.text onPort:5566 withTimeout:30 error:nil];        }                //发送消息        - (IBAction)sendClick:(id)sender {            NSData *data = [self.sendField.text dataUsingEncoding:NSUTF8StringEncoding];            [_sendSocket writeData:data withTimeout:30 tag:0];            self.sendField.text = @"";        }                - (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port        {            NSLog(@"连接服务器成功");        }                - (void)onSocketDidDisconnect:(AsyncSocket *)sock        {            NSLog(@"断开连接");        }                                - (void)dealloc {            [ipField release];            [sendField release];            [msgView release];            [ipField release];            [super dealloc];        }                - (void)viewDidUnload {            [self setIpField:nil];            [super viewDidUnload];        }        @end