iOS网络编程实践--NSStream实现TCP Socket iPhone客户端

客户端我们使用iPhone应用程序，画面比较简单。点击发送按钮，给服务器发送一些字符串过去。点击接收按钮就会从服务器读取一些字符串，并且显示在画面上。

 

有关客户端应用的UI部分不再介绍了，我们直接看代码部分，Socket客户端可以采用CFStream或NSStream实现，CFStream 实现方式与服务器端基本一样。为了给读者介绍更多的知识，本例我们采用NSStream实现。NSStream实现采用Objective-C语言，一些 面向对象的类。

下面我们看看客户端视图控制器ViewController.h

#import <CoreFoundation/CoreFoundation.h>



#include <sys/socket.h>



#include <netinet/in.h>



 



#define PORT 9000



 



@interface ViewController : UIViewController<NSStreamDelegate>



{



int flag ; //操作标志 0为发送 1为接收



}



 



@property (nonatomic, retain) NSInputStream *inputStream;



@property (nonatomic, retain) NSOutputStream *outputStream;



 



@property (weak, nonatomic) IBOutlet UILabel *message;



 



- (IBAction)sendData:(id)sender;



- (IBAction)receiveData:(id)sender;



 



@end

 

定义属性inputStream和outputStream，它们输入流NSInputStream和输出流NSOutputStream类。它们与服务器CFStream实现中的输入流CFReadStreamRef和输出流CFWriteStreamRef对应的。

视图控制器ViewController.m的初始化网络方法initNetworkCommunication代码：

- (void)initNetworkCommunication



{



CFReadStreamRef readStream;



CFWriteStreamRef writeStream;



CFStreamCreatePairWithSocketToHost(NULL,



(CFStringRef)@”192.168.1.103″, PORT, &readStream, &writeStream);   ①



_inputStream = (__bridge_transfer NSInputStream *)readStream; ②



_outputStream = (__bridge_transfer NSOutputStream*)writeStream;  ③



[_inputStream setDelegate:self];  ④



[_outputStream setDelegate:self];  ⑤



[_inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]



forMode:NSDefaultRunLoopMode]; ⑥



[_outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]



forMode:NSDefaultRunLoopMode];  ⑦



[_inputStream open];  ⑧



[_outputStream open];  ⑨



}

 

 

点击发送和接收按钮触发的方法如下：

/* 点击发送按钮  */



- (IBAction)sendData:(id)sender {



flag = 0;



[self initNetworkCommunication];



}



/* 点击接收按钮  */



- (IBAction)receiveData:(id)sender {



flag = 1;



[self initNetworkCommunication];



}

 

它们都调用initNetworkCommunication方法，并设置操作标识flag，如果flag为0发送数据，flag为1接收数据。

流的状态的变化触发很多事件，并回调NSStreamDelegate协议中定义的方法stream:handleEvent:，其代码如下：

-(void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {



NSString *event;



switch (streamEvent) {



case NSStreamEventNone:



event = @”NSStreamEventNone”;



break;



case NSStreamEventOpenCompleted:



event = @”NSStreamEventOpenCompleted”;



break;



case NSStreamEventHasBytesAvailable:



event = @”NSStreamEventHasBytesAvailable”;



if (flag ==1 && theStream == _inputStream) {



NSMutableData *input = [[NSMutableData alloc] init];



uint8_t buffer[1024];  ①



int len;



while([_inputStream hasBytesAvailable]) ②



{



len = [_inputStream read:buffer maxLength:sizeof(buffer)];  ③



if (len > 0)



{



[input appendBytes:buffer length:len];



}



}



NSString *resultstring = [[NSString alloc]



initWithData:input encoding:NSUTF8StringEncoding];



NSLog(@”接收:%@”,resultstring);



_message.text = resultstring;



}



break;



case NSStreamEventHasSpaceAvailable:



event = @”NSStreamEventHasSpaceAvailable”;



if (flag ==0 && theStream == _outputStream) {



//输出



UInt8 buff[] = ”Hello Server!”; ④



[_outputStream write:buff maxLength: strlen((const char*)buff)+1]; ⑤



//关闭输出流



[_outputStream close];



}



break;



case NSStreamEventErrorOccurred:



event = @”NSStreamEventErrorOccurred”;



[self close]; ⑥



break;



case NSStreamEventEndEncountered:



event = @”NSStreamEventEndEncountered”;



NSLog(@”Error:%d:%@”,[[theStream streamError] code],



[[theStream streamError] localizedDescription]);



break;



default:



[self close];  ⑦



event = @”Unknown”;



break;



}



NSLog(@”event——%@”,event);



}

 

在读取数据分支（NSStreamEventHasBytesAvailable）中，代码第①行为读取数据准备缓冲区，本例中设置的是1024个字节，这个大小会对流的读取有很多的影响。第②行代码使用hasBytesAvailable方法判断是否流有数据可以读，如果有可读数据就进行循环读取。第③行代码使用流的read:maxLength:方法读取数据到缓冲区，第1个参数是缓冲区对象buffer，第2个参数是读取的缓冲区的字节长度。

在写入数据分支（NSStreamEventHasSpaceAvailable）中，代码第④行是要写入的数据，第⑤行代码 [_outputStream write:buff maxLength: strlen((const char*)buff)+1]是写如数据方 法。

第⑥和第⑦行代码[self close]调用close方法关闭，close方法代码如下：

-(void)close



{



[_outputStream close];



[_outputStream removeFromRunLoop:[NSRunLoop currentRunLoop]



forMode:NSDefaultRunLoopMode];



[_outputStream setDelegate:nil];



[_inputStream close];



[_inputStream removeFromRunLoop:[NSRunLoop currentRunLoop]



forMode:NSDefaultRunLoopMode];



[_inputStream setDelegate:nil];



}