iOS Socket通信

用socket从服务器上获取数据，有以下三种方法：
第一种是使用封装好的第三方GCDAsyncSocket，下载地址是https://github.com/Yuzeyang/GCDAsyncSocketManager
，在网上可以搜到它的使用方法（有很多）。

第二种是使用系统自带的方法，代码如下

#import "SocketManager.h"

@interface SocketManager ()<NSStreamDelegate>
{
    NSInputStream *inputStream;
    NSOutputStream *outputStream;
}
@end
@implementation SocketManager

+ (instancetype)sharedSocketManager {
    static SocketManager *socketManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        socketManager = [[SocketManager alloc] init];
    });
    return socketManager;
}

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode{

    NSLog(@"eventCode:%lu",(unsigned long)eventCode);
    switch (eventCode) {
        case NSStreamEventOpenCompleted:
            
              NSLog(@"输入输出流打开完成");
            
            break;
          case NSStreamEventHasBytesAvailable:

              NSLog(@"有字节可读");
                 [self readData];
            
            break;
           case NSStreamEventHasSpaceAvailable:
            
              NSLog(@"可以发送字节");
            
                 break;
             case NSStreamEventErrorOccurred:
            
              NSLog(@" 连接出现错误");
                 break;
            case NSStreamEventEndEncountered:
            
              NSLog(@"连接结束");
            
                 // 关闭输入输出流
                 [inputStream close];
                 [outputStream close];
    
                 // 从主运行循环移除
                 [inputStream removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
                 [outputStream removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
                 break;
             default:
                 break;
     }

}

- (void)connect{
   
    NSString *host = IP地址;
    int port = 端口号;
    
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
    CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)host, port, &readStream, &writeStream);
    
     inputStream = (__bridge NSInputStream *)(readStream);
     outputStream = (__bridge NSOutputStream *)(writeStream);
    
    inputStream.delegate = self;
    outputStream.delegate = self;
    
    [inputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
    [outputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
    
    [inputStream open];
    [outputStream open];
    
}

- (void)login{
    写入的命令，此处省略
    [outputStream write:data.bytes maxLength:data.length];
}


- (void)readData{
        uint8_t buf[1024];
    
        NSInteger len = [inputStream read:buf maxLength:sizeof(buf)];
        NSData *data = [NSData dataWithBytes:buf length:len];
        
        NSString *recStr =  [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
        
        NSLog(@"%@",recStr);
//    [self cleanUpStream:inputStream];
}
- (void)cleanUpStream:(NSStream *)stream
{
    [stream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [stream close];
    
    stream = nil;
}
@end

第三种方法是使用socket编程最底层的connect等方法，参考地址：http://blog.csdn.net/majiakun1/article/details/19357415
，代码如下：

#import "SocketManager1.h"
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <syslog.h>
#include <errno.h>
#include <stdlib.h>
@implementation SocketManager1

- (void)socketConnect:(NSString *)host Port:(int)port{

    const char *ip = IP地址;
    self.socketFD = socket(AF_INET, SOCK_STREAM, 0);
    NSData *dataLogin = [self login];
    NSInteger bytes = [dataLogin length];
    NSLog(@"socketFD:%d",self.socketFD);
    struct sockaddr_in nativeAdd;
    nativeAdd.sin_len = sizeof(struct sockaddr);
    nativeAdd.sin_family = AF_INET;
    nativeAdd.sin_port = htons(port);
    nativeAdd.sin_addr.s_addr = inet_addr(ip);

    self.status = connect(self.socketFD, (struct sockaddr *) &nativeAdd, sizeof(nativeAdd));
    if (-1 == self.status) {
        close(self.socketFD);
    }
    if (self.status <0) {
        NSLog(@"连接失败:%d",errno);
        
    }else{
    
        NSLog(@"连接成功:%d",self.status);
        self.status = write(self.socketFD, [dataLogin bytes], bytes);
        if (self.status <0) {
            NSLog(@"写入失败:%d",errno);
            
        }else{
            
            NSLog(@"登陆成功:%d",self.status);
            
            [self read];
        }

    }
  
}

- (void)read{
    [NSThread detachNewThreadSelector:@selector(thread:) toTarget:self withObject:@"thread1"];
}

- (void)thread:(NSString *)sender{
    
    NSThread *thread = [NSThread currentThread];
    NSLog(@"%@",thread);
  NSMutableData *data = [[NSMutableData alloc]init];
    BOOL waitingForData = YES;
    int i = 0;
    do {
        const char *buffer[10000];
        int length = sizeof(buffer);
        int result = read(self.socketFD, &buffer, length);
        NSLog(@"result:%d",result);
        if (result >0) {
            [data appendBytes:buffer length:result];
            NSLog(@"data:%@",data);
            
        }else{
            
            NSString *string = [[NSString alloc]initWithData:data encoding:NSASCIIStringEncoding];
            NSLog(@"string:%@",string);
            waitingForData = NO;
        }
        
        ++i;
        NSLog(@"i:%d",i);
       NSLog(@"waitingForData:%d",waitingForData);
    } while (waitingForData == YES);

}
- (NSData *)login{
  写入的命令，此处省略；
    return data;
}

注：服务器状态码
1XX - 服务器的信息
2XX - 表示请求成功
200：请求成功
201：成功创建连接
202：接受请求
3XX - 表示重定向
302：表示重定向
304：表示服务端资源没有变化，访问缓存
问题 - 这次请求没有真正低访问服务器端
305：使用代理
4XX - 客户端错误
400：错误的请求
404：网页找不到
403：拒绝访问
405：请求类型不允许
5XX - 服务端错误
500：服务端错误
502：路径错误
504：请求超时
505：http版本不支持