iOS编程中socket

• 前言
• AsyncSocket介绍
• AsyncSocket详解
• AsyncSocket示例

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一、前言

公司的项目用到了Socket编程，之前在学习的过程当中，用到的更多的还是http请求的方式。但是既然用到了就必须学习一下，所以就在网上找一些例子，然后想自己写一个demo。可是发现很多写iOS Socket的博客并没有很详细的说明，也可能是大神们觉得其他东西都浅显易懂。

自己专研了一下，将自己的一些理解总结出来，一方面整理自己的学习思路，另一方面，为一些和我有同样困惑的小伙伴们，稍做指引。

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二、AsyncSocket介绍

1⃣️iOS中Socket编程的方式有哪些？

－BSD Socket

BSD Socket 是UNIX系统中通用的网络接口，它不仅支持各种不同的网络类型，而且也是一种内部进程之间的通信机制。而iOS系统其实本质就是UNIX，所以可以用，但是比较复杂。

－CFSocket

CFSocket是苹果提供给我们的使用Socket的方式，但是用起来还是会不太顺手。当然想使用的话，可以细细研究一下。

－AsyncSocket

这次博客的主讲内容，也是我们在开发项目中经常会用到的。

2⃣️为什么选择AsyncSocket？

iphone的CFNetwork编程比较艰深。使用AsyncSocket开源库来开发相对较简单，帮助我们封装了很多东西。

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三、AsyncSocket详解

1⃣️说明

在我们开发当中，我们主要的任务是开发客户端。所以详解里主要将客户端的整个连接建立过程，以及在说明时候回调哪些函数。在后面的示例代码中，也会给出服务器端的简单开发。

2⃣️过程详解

1.建立连接

- (int)connectServer:(NSString *)hostIP port:(int)hostPort

2.连接成功后，会回调的函数

- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port

3.发送数据

- (void)writeData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag;

4.接受数据

-(void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag

5.断开连接

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

- (void)onSocketDidDisconnect:(AsyncSocket *)sock

主要就是上述的几个方法，只是说在真正开发当中，很可能我们在收发数据的时候，我们收发的数据并不仅仅是一个字符串包装成NSData即可，我们很可能会发送结构体等类型，这个时候我们就需要和服务器端的人员协作来开发：定义怎样的结构体。

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四、AsyncSocket示例

客户端代码

#import "ViewController.h"

#define SRV_CONNECTED 0
#define SRV_CONNECT_SUC 1
#define SRV_CONNECT_FAIL 2
#define HOST_IP @"192.168.83.40"
#define HOST_PORT 8008

@interface ViewController ()
{
    NSString *_content;
}
-(int) connectServer: (NSString *) hostIP port:(int) hostPort;
-(void)showMessage:(NSString *) msg;
@end

@implementation ViewController

@synthesize clientSocket,tbInputMsg,lblOutputMsg;

#pragma mark - view lifecycle
- (void)viewDidLoad
{
    [super viewDidLoad];
    
    [self connectServer:HOST_IP port:HOST_PORT];
}
- (void)viewDidUnload
{
    [super viewDidUnload];
    [clientSocket release], clientSocket = nil;
    [tbInputMsg release], tbInputMsg = nil;
    [lblOutputMsg release], lblOutputMsg = nil;
}

- (int)connectServer:(NSString *)hostIP port:(int)hostPort
{
    if (clientSocket == nil)
    {
        // 在需要联接地方使用connectToHost联接服务器
        clientSocket = [[AsyncSocket alloc] initWithDelegate:self];
        NSError *err = nil;
        if (![clientSocket connectToHost:hostIP onPort:hostPort error:&err])
        {
            NSLog(@"Error %d:%@", err.code, [err localizedDescription]);
            
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[@"Connection failed to host" stringByAppendingString:hostIP] message:[NSString stringWithFormat:@"%d:%@",err.code,err.localizedDescription] delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
            [alert show];
            [alert release];
            return SRV_CONNECT_FAIL;
        } else {
            NSLog(@"Connected!");
            return SRV_CONNECT_SUC;
        }
    }
    else {
        return SRV_CONNECTED;
    }
}

#pragma mark - IBAction
// 发送数据
- (IBAction) sendMsg:(id)sender
{
    NSString *inputMsgStr = tbInputMsg.text;
    NSString * content = [inputMsgStr stringByAppendingString:@"\r\n"];
    NSLog(@"%@",content);
    NSData *data = [content dataUsingEncoding:NSUTF8StringEncoding];
    // NSData *data = [content dataUsingEncoding:NSISOLatin1StringEncoding];
    [clientSocket writeData:data withTimeout:-1 tag:0];
}
// 连接/重新连接
- (IBAction) reconnect:(id)sender
{
    int stat = [self connectServer:HOST_IP port:HOST_PORT];
    switch (stat) {
        case SRV_CONNECT_SUC:
            [self showMessage:@"connect success"];
            break;
        case SRV_CONNECTED:
            [self showMessage:@"It's connected,don't agian"];
            break;
        default:
            break;
    }
}
- (void)showMessage:(NSString *)msg
{
    UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"Alert!"
                                                    message:msg
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
    [alert show];
    [alert release];
}
- (IBAction)textFieldDoneEditing:(id)sender
{
    [tbInputMsg resignFirstResponder];
}
- (IBAction)backgroundTouch:(id)sender
{
    [tbInputMsg resignFirstResponder];
}

#pragma mark socket delegate
- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port
{
    [clientSocket readDataWithTimeout:-1 tag:0];
}

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

- (void)onSocketDidDisconnect:(AsyncSocket *)sock
{
    NSString *msg = @"Sorry this connect is failure";
    [self showMessage:msg];
    [msg release];
    clientSocket = nil;
}

- (void)onSocketDidSecure:(AsyncSocket *)sock
{
}

// 接收到数据（可以通过tag区分）
-(void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    NSString* aStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    _content = lblOutputMsg.text;
    NSLog(@"Hava received datas is :%@",aStr);
    NSString *newStr = [NSString stringWithFormat:@"\n%@", aStr];
    lblOutputMsg.text = [_content stringByAppendingString:newStr];
    [aStr release];
    [clientSocket readDataWithTimeout:-1 tag:0];
}

@end

服务端代码

#import "SocketView.h"
#import "AsyncSocket.h"

#define WELCOME_MSG  0
#define ECHO_MSG     1

#define FORMAT(format, ...) [NSString stringWithFormat:(format), ##__VA_ARGS__]

@interface SocketView (PrivateAPI)
- (void)logError:(NSString *)msg;
- (void)logInfo:(NSString *)msg;
- (void)logMessage:(NSString *)msg;
@end

@implementation SocketView

// 初始化
- (void)awakeFromNib
{
    listenSocket = [[AsyncSocket alloc] initWithDelegate:self];
    [listenSocket setRunLoopModes:[NSArray arrayWithObject:NSRunLoopCommonModes]];
    
    connectedSockets = [[NSMutableArray alloc] initWithCapacity:1];
    isRunning = NO;
    
    [logView setString:@""];
    // [portField setString:@"8080"];
}

- (IBAction)startStop:(id)sender
{
    if(!isRunning)
    {
        int port = [portField intValue];
        
        if(port < 0 || port > 65535)
        {
            port = 0; // 会随即取端口
        }
        
        NSError *error = nil;
        if(![listenSocket acceptOnPort:port error:&error])
        {
            [self logError:FORMAT(@"Error starting server: %@", error)];
            return;
        }
        
        [self logInfo:FORMAT(@"Echo server started on port %hu", [listenSocket localPort])];
        isRunning = YES;
        
        [portField setEnabled:NO];
        [startStopButton setTitle:@"Stop"];
    }
    else
    {
        // Stop accepting connections
        [listenSocket disconnect];
        
        // Stop any client connections
        int i;
        for(i = 0; i < [connectedSockets count]; i++)
        {
            // Call disconnect on the socket,
            // which will invoke the onSocketDidDisconnect: method,
            // which will remove the socket from the list.
            [[connectedSockets objectAtIndex:i] disconnect];
        }
        
        [self logInfo:@"Stopped Echo server"];
        isRunning = false;
        
        [portField setEnabled:YES];
        [startStopButton setTitle:@"Start"];
    }
}

- (void)scrollToBottom
{
    NSScrollView *scrollView = [logView enclosingScrollView];
    NSPoint newScrollOrigin;
    
    if ([[scrollView documentView] isFlipped])
        newScrollOrigin = NSMakePoint(0.0, NSMaxY([[scrollView documentView] frame]));
    else
        newScrollOrigin = NSMakePoint(0.0, 0.0);
    
    [[scrollView documentView] scrollPoint:newScrollOrigin];
}

- (void)logError:(NSString *)msg
{
    NSString *paragraph = [NSString stringWithFormat:@"%@\n", msg];
    
    NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithCapacity:1];
    [attributes setObject:[NSColor redColor] forKey:NSForegroundColorAttributeName];
    
    NSAttributedString *as = [[NSAttributedString alloc] initWithString:paragraph attributes:attributes];
    [as autorelease];
    
    [[logView textStorage] appendAttributedString:as];
    [self scrollToBottom];
}

- (void)logInfo:(NSString *)msg
{
    NSString *paragraph = [NSString stringWithFormat:@"%@\n", msg];
    
    NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithCapacity:1];
    [attributes setObject:[NSColor purpleColor] forKey:NSForegroundColorAttributeName];
    
    NSAttributedString *as = [[NSAttributedString alloc] initWithString:paragraph attributes:attributes];
    [as autorelease];
    
    [[logView textStorage] appendAttributedString:as];
    [self scrollToBottom];
}

- (void)logMessage:(NSString *)msg
{
    NSString *paragraph = [NSString stringWithFormat:@"%@\n", msg];
    
    NSMutableDictionary *attributes = [NSMutableDictionary dictionaryWithCapacity:1];
    [attributes setObject:[NSColor blackColor] forKey:NSForegroundColorAttributeName];
    
    NSAttributedString *as = [[NSAttributedString alloc] initWithString:paragraph attributes:attributes];
    [as autorelease];
    
    [[logView textStorage] appendAttributedString:as];
    [self scrollToBottom];
}

- (void)onSocket:(AsyncSocket *)sock didAcceptNewSocket:(AsyncSocket *)newSocket
{
    [connectedSockets addObject:newSocket];
}

// 客户连接成功！
- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port
{
    [self logInfo:FORMAT(@"Accepted client %@:%hu", host, port)];
    
    NSString *welcomeMsg = @"恭喜您,已经通过scoket连接上服务器!";
    NSData *welcomeData = [welcomeMsg dataUsingEncoding:NSUTF8StringEncoding];
    
    [sock writeData:welcomeData withTimeout:-1 tag:WELCOME_MSG];
    
    // We could call readDataToData:withTimeout:tag: here - that would be perfectly fine.
    // If we did this, we'd want to add a check in onSocket:didWriteDataWithTag: and only
    // queue another read if tag != WELCOME_MSG.
}

- (void)onSocket:(AsyncSocket *)sock didWriteDataWithTag:(long)tag
{
   [sock readDataToData:[AsyncSocket CRLFData] withTimeout:-1 tag:0];
}
// 接收到数据
- (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    NSData *strData = [data subdataWithRange:NSMakeRange(0, [data length] - 2)];
    NSString *recvMsg = [[[NSString alloc] initWithData:strData encoding:NSUTF8StringEncoding] autorelease];
    if(recvMsg)
    {
        [self logMessage:recvMsg];
    }
    else
    {
        [self logError:@"Error converting received data into UTF-8 String"];
    }
    NSString *backStr = nil;
    for (AsyncSocket *socket in connectedSockets) {
        if ([sock isEqualTo:socket]) {
            backStr = [NSString stringWithFormat:@"我说: %@",recvMsg];
        } else {
            backStr = [NSString stringWithFormat:@"他说: %@",recvMsg];
        }
    }
    
    // 回发数据
    NSData* backData = [backStr dataUsingEncoding:NSUTF8StringEncoding];
    [sock writeData:backData withTimeout:-1 tag:ECHO_MSG];
}

- (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err
{
    [self logInfo:FORMAT(@"Client Disconnected: %@:%hu", [sock connectedHost], [sock connectedPort])];
}

- (void)onSocketDidDisconnect:(AsyncSocket *)sock
{
    [connectedSockets removeObject:sock];
}

@end