下载 AsyncSocket
引入 AsyncSocket.h
     AsyncSocket.h
|-- RootViewController.h
#import
#import "AsyncSocket.h"
@interface RootViewController : UIViewController

{
    AsyncSocket *_asySocket;
    NSMutableData *_data;
}
@property (nonatomic,retain) AsyncSocket *asySocket;
@property (nonatomic,retain) NSMutableData *data;
@end

|-- RootViewController.m
#import "RootViewController.h"

@interface RootViewController ()

@end

@implementation RootViewController

-(void)loadView
{
    [super loadView];
    self.view.backgroundColor = [UIColor orangeColor];
}
- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    UIButton *socketBtn = [[UIButton alloc]initWithFrame:CGRectMake(50, 50, 100, 40)];
    [socketBtn setTitle:@"socketTitle" forState:UIControlStateNormal];
    [socketBtn setBackgroundColor:[UIColor greenColor]];
    [socketBtn addTarget:self action:@selector(socketAction) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:socketBtn];
    [socketBtn release];
   
    UITextField *text = [[UITextField alloc]initWithFrame:CGRectMake(100, 100, 200, 40)];
    text.backgroundColor = [UIColor blueColor];
    [text addTarget:self action:@selector(textAction) forControlEvents:UIControlEventEditingChanged];
    [self.view addSubview:text];
    [text release];
   
   
}
-(void)socketAction
{
   
    _asySocket = [[AsyncSocket alloc]initWithDelegate:self];
    NSError *error = [[NSError alloc]init];
    if (![_asySocket connectToHost:@"www.baidu.com" onPort:80 error:&error]) {
        NSLog(@"error:%@",error);
    }
   
   
    //_data=[[NSMutableData dataWithLength:50] retain];
   
    [_asySocket readDataToLength:50 withTimeout:5 tag:1];
    [_asySocket readDataToLength:50 withTimeout:5 tag:2];
    [_asySocket writeData:[@"GET / HTTP/1.1\n\n" dataUsingEncoding:NSUTF8StringEncoding] withTimeout:3 tag:1];

   
}
-(void)textAction
{
    NSLog(@"textAction ...");
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


#pragma mark -- AsyncSocket Delegate

//创建了新的Socket用于处理和客户端的请求，如果这个新socket实例你不打算保留（retain），
//那么将拒绝和该客户端连接
- (void)onSocket:(AsyncSocket *)sock didAcceptNewSocket:(AsyncSocket *)newSocket{
    if (!_asySocket) {
        _asySocket=[newSocket retain];
        NSLog(@"did accept new socket");
    }
}

//提供线程的runloop实例给AsyncSocket，后者将使用这个runloop执行socket通讯的操作
- (NSRunLoop *)onSocket:(AsyncSocket *)sock wantsRunLoopForNewSocket:(AsyncSocket *)newSocket{
    NSLog(@"wants runloop for new socket.");
    return [NSRunLoop currentRunLoop];
}

- (BOOL)onSocketWillConnect:(AsyncSocket *)sock{
    NSLog(@"will connect");
    return YES;
}

- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port{
    NSLog(@"did connect to host");
    [_asySocket readDataWithTimeout:-1 tag:1];
}


//[_asySocket readDataToLength:50 withTimeout:5 tag:1];
//这句话主要是回调函数来读取数据
- (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag{
    NSLog(@"did read data");
    NSString* message = [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] autorelease];
    NSLog(@"message is: \n%@",message);
    [_asySocket writeData:data withTimeout:2 tag:1];
}

//[_asySocket writeData:[@"GET / HTTP/1.1\n\n" dataUsingEncoding:NSUTF8StringEncoding] withTimeout:3 tag:1];
//回调这个函数
- (void)onSocket:(AsyncSocket *)sock didWriteDataWithTag:(long)tag{
    NSLog(@"message did write");
    [_asySocket readDataWithTimeout:-1 tag:1];
}

- (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err{
    NSLog(@"onSocket:%p willDisconnectWithError:%@", sock, err);
}

- (void)onSocketDidDisconnect:(AsyncSocket *)sock{
    NSLog(@"socket did disconnect");
    [_asySocket release];
    _asySocket=nil;
}
@end