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Socket描述了一个IP、端口对。它简化了程序员的操作,知道对方的IP以及PORT就可以给对方发送消息,再由服务器端来处理发送的这些消息。所以,Socket一定包含了通信的双发,即客户端(Client)与服务端(server)。
1)服务端利用Socket监听端口;
2)客户端发起连接;
3)服务端返回信息,建立连接,开始通信;
4)客户端,服务端断开连接。
1套接字(socket)概念
套接字(socket)是通信的基石,是支持TCP/IP协议的网络通信的基本操作单元。
应用层通过传输层进行数据通信时,TCP会遇到同时为多个应用程序进程提供并发服务的问题。多个TCP连接或多个应用程序进程可能需要通过同一个
TCP协议端口传输数据。为了区别不同的应用程序进程和连接,许多计算机操作系统为应用程序与TCP/IP协议交互提供了套接字(Socket)接口。应
用层可以和传输层通过Socket接口,区分来自不同应用程序进程或网络连接的通信,实现数据传输的并发服务。
2 建立socket连接
建立Socket连接至少需要一对套接字,其中一个运行于客户端,称为ClientSocket,另一个运行于服务器端,称为ServerSocket。
套接字之间的连接过程分为三个步骤:服务器监听,客户端请求,连接确认。
服务器监听:服务器端套接字并不定位具体的客户端套接字,而是处于等待连接的状态,实时监控网络状态,等待客户端的连接请求。
客户端请求:指客户端的套接字提出连接请求,要连接的目标是服务器端的套接字。为此,客户端的套接字必须首先描述它要连接的服务器的套接字,指出服务器端套接字的地址和端口号,然后就向服务器端套接字提出连接请求。
连接确认:当服务器端套接字监听到或者说接收到客户端套接字的连接请求时,就响应客户端套接字的请求,建立一个新的线程,把服务器端套接字的描述发
给客户端,一旦客户端确认了此描述,双方就正式建立连接。而服务器端套接字继续处于监听状态,继续接收其他客户端套接字的连接请求。
4、SOCKET连接与TCP连接
创建Socket连接时,可以指定使用的传输层协议,Socket可以支持不同的传输层协议(TCP或UDP),当使用TCP协议进行连接时,该Socket连接就是一个TCP连接。
5、Socket连接与HTTP连接
由于通常情况下Socket连接就是TCP连接,因此Socket连接一旦建立,通信双方即可开始相互发送数据内容,直到双方连接断开。但在实际网
络应用中,客户端到服务器之间的通信往往需要穿越多个中间节点,例如路由器、网关、防火墙等,大部分防火墙默认会关闭长时间处于非活跃状态的连接而导致
Socket 连接断连,因此需要通过轮询告诉网络,该连接处于活跃状态。
而HTTP连接使用的是“请求—响应”的方式,不仅在请求时需要先建立连接,而且需要客户端向服务器发出请求后,服务器端才能回复数据。
很多情况下,需要服务器端主动向客户端推送
iphone的标准推荐CFNetwork
C库编程.但是编程比较烦躁。在其它OS往往用类来封装的对Socket函数的处理。比如MFC的CAsysncSocket.在iphone也有类似于
开源项目.cocoa AsyncSocket库, 官方网站:http://code.google.com/p/cocoaasyncsocket/ 它用来简化
CFnetwork的调用.
一.在项目引入ASyncSocket库
1.下载ASyncSocket库源码
2.把ASyncSocket库源码加入项目:只需要增加RunLoop目录中的AsyncSocket.h、AsyncSocket.m、AsyncUdpSocket.h和AsyncUdpSocket.m四个文件。
3.在项目增加CFNetwork框架
在Framework目录右健,选择Add-->Existing Files... , 选择 CFNetwork.framework
二.TCP客户端
1. 在controller头文件定义AsyncSocket对象
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#import #import "AsyncSocket.h"
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@interface HelloiPhoneViewController : UIViewController {
UITextField * textField; AsyncSocket * asyncSocket;}@property
(retain, nonatomic) IBOutlet UITextField *textField;- (IBAction)
buttonPressed: (id)sender;- (IBAction) textFieldDoneEditing:
(id)sender;
@end
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2.在需要联接地方使用connectToHost联接服务器
其中initWithDelegate的参数中self是必须。这个对象指针中的各个Socket响应的函数将被ASyncSocket所调用.
asyncSocket = [[AsyncSocket alloc] initWithDelegate:self];
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NSError *err = nil; if(![asyncSocket connectToHost:host on:port
error:&err]) { NSLog(@"Error: %@", err); }
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3.增加Socket响应事件
因为initWithDelegate把将当前对象传递进去,这样只要在当前对象方法实现相应方法.
4.关于NSData对象
无论SOCKET收发都采用NSData对象.
NSData主要是带一个(id)data指向的数据空间和长度 length.
NSString 转换成NSData 对象
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NSData* xmlData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding];
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NSData 转换成NSString对象
NSData * data;
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NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
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4.发送数据
AsyncSocket writeData 方法来发送数据,它有如下定义
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- (void)writeDataNSData *)data withTimeoutNSTimeInterval)timeout taglong)tag;
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以下是一个实例语句.
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NSData* aData= [@"test data" dataUsingEncoding: NSUTF8StringEncoding]; [sock writeData:aData withTimeout:-1 tag:1];
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在onSocket重载函数,有如定义采用是专门用来处理SOCKET的发送数据的:
-(void)onSocket(AsyncSocket *)sock didWriteDataWithTag:(long)tag
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{ NSLog(@"thread(%),onSocket:%p didWriteDataWithTag:%d",[[NSThread currentThread] name], sock,tag);}
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5.接收Socket数据.
在onSocket重载函数,有如定义采用是专门用来处理SOCKET的接收数据的.
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-(void) onSocketAsyncSocket *)sock didReadDataNSData *)data withTaglong)tag
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在中间将其转换成NSString进行显示.
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NSString* aStr = [[NSString alloc] initWithData:data
encoding:NSUTF8StringEncoding]; NSLog(@"===%@",aStr); [aStr
release];
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//
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// SocketDemoViewController.h
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// SocketDemo
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//
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// Created by xiang xiva on 10-7-10.
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// Copyright 2010 __MyCompanyName__. All rights reserved.
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//
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#import <UIKit/UIKit.h>
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#import "AsyncSocket.h"
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#define SRV_CONNECTED 0
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#define SRV_CONNECT_SUC 1
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#define SRV_CONNECT_FAIL 2
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#define HOST_IP @"192.168.110.1"
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#define HOST_PORT 8080
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@interface SocketDemoViewController : UIViewController {
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UITextField *inputMsg;
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UILabel *outputMsg;
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AsyncSocket *client;
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}
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@property (nonatomic, retain) AsyncSocket *client;
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@property (nonatomic, retain) IBOutlet UITextField *inputMsg;
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@property (nonatomic, retain) IBOutlet UILabel *outputMsg;
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- (int) connectServer: (NSString *) hostIP port:(int) hostPort;
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- (void) showMessage:(NSString *) msg;
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- (IBAction) sendMsg;
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- (IBAction) reConnect;
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- (IBAction) textFieldDoneEditing:(id)sender;
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- (IBAction) backgroundTouch:(id)sender;
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@end
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//
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// SocketDemoViewController.m
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// SocketDemo
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//
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// Created by xiang xiva on 10-7-10.
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// Copyright 2010 __MyCompanyName__. All rights reserved.
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//
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#import "SocketDemoViewController.h"
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@implementation SocketDemoViewController
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@synthesize inputMsg, outputMsg;
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@synthesize client;
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/*
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// The designated initializer. Override to perform setup that is required before the view is loaded.
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- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
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self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
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if (self) {
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// Custom initialization
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}
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return self;
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}
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*/
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/*
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// Implement loadView to create a view hierarchy programmatically, without using a nib.
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- (void)loadView {
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}
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*/
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// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
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- (void)viewDidLoad {
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//[super viewDidLoad];
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[self connectServer:HOST_IP port:HOST_PORT];
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//监听读取
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}
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// Override to allow orientations other than the default portrait orientation.
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- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
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return YES;
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}
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- (void)didReceiveMemoryWarning {
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// Releases the view if it doesn‘t have a superview.
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[super didReceiveMemoryWarning];
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// Release any cached data, images, etc that aren‘t in use.
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}
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- (void)viewDidUnload {
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self.client = nil;
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// Release any retained subviews of the main view.
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// e.g. self.myOutlet = nil;
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}
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- (int) connectServer: (NSString *) hostIP port:(int) hostPort{
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if (client == nil) {
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client = [[AsyncSocket alloc] initWithDelegate:self];
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NSError *err = nil;
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//192.168.110.128
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if (![client connectToHost:hostIP onPort:hostPort error:&err]) {
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NSLog(@"%@ %@", [err code], [err localizedDescription]);
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UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[@"Connection failed to host "
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stringByAppendingString:hostIP]
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message:[[[NSString alloc]initWithFormat:@"%@",[err code]] stringByAppendingString:[err localizedDescription]]
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delegate:self
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cancelButtonTitle:@"OK"
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otherButtonTitles:nil];
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[alert show];
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[alert release];
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//client = nil;
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return SRV_CONNECT_FAIL;
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} else {
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NSLog(@"Conectou!");
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return SRV_CONNECT_SUC;
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}
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}
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else {
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[client readDataWithTimeout:-1 tag:0];
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return SRV_CONNECTED;
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}
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}
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- (IBAction) reConnect{
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int stat = [self connectServer:HOST_IP port:HOST_PORT];
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switch (stat) {
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case SRV_CONNECT_SUC:
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[self showMessage:@"connect success"];
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break;
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case SRV_CONNECTED:
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[self showMessage:@"It‘s connected,don‘t agian"];
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break;
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default:
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break;
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}
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}
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- (IBAction) sendMsg{
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NSString *inputMsgStr = self.inputMsg.text;
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NSString * content = [inputMsgStr stringByAppendingString:@"\r\n"];
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NSLog(@"%a",content);
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NSData *data = [content dataUsingEncoding:NSISOLatin1StringEncoding];
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[client writeData:data withTimeout:-1 tag:0];
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//[data release];
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//[content release];
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//[inputMsgStr release];
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//继续监听读取
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//[client readDataWithTimeout:-1 tag:0];
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}
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#pragma mark -
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#pragma mark close Keyboard
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- (IBAction) textFieldDoneEditing:(id)sender{
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[sender resignFirstResponder];
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}
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- (IBAction) backgroundTouch:(id)sender{
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[inputMsg resignFirstResponder];
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}
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#pragma mark socket uitl
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- (void) showMessage:(NSString *) msg{
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UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"Alert!"
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message:msg
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delegate:nil
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cancelButtonTitle:@"OK"
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otherButtonTitles:nil];
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[alert show];
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[alert release];
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}
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#pragma mark socket delegate
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- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port{
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[client readDataWithTimeout:-1 tag:0];
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}
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- (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err
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{
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NSLog(@"Error");
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}
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- (void)onSocketDidDisconnect:(AsyncSocket *)sock
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{
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NSString *msg = @"Sorry this connect is failure";
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[self showMessage:msg];
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[msg release];
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client = nil;
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}
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- (void)onSocketDidSecure:(AsyncSocket *)sock{
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}
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- (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag{
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NSString* aStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
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NSLog(@"Hava received datas is :%@",aStr);
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self.outputMsg.text = aStr;
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[aStr release];
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[client readDataWithTimeout:-1 tag:0];
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}
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#pragma mark dealloc
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- (void)dealloc {
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[client release];
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[inputMsg release];
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[outputMsg release];
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[super dealloc];
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}
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@end
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01-socket第三方库 AsyncSocket(GCDAsyncSocket)
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原文地址:http://www.cnblogs.com/iyuanxiaojun/p/4513628.html