IOS socket编程 - NSStream不工作

问题描述：

我使用的是被称为具有IP地址的WiFly设备：169.254.1.1和端口2000年。我试图连接到该设备通过iOS应用程序。我用下面的代码连接：IOS socket编程 - NSStream不工作

CFReadStreamRef readStream; 
CFWriteStreamRef writeStream; 

UInt32 port = 2000; 
CFStringRef host = CFSTR("169.254.1.1"); 

CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host, port, &readStream, &writeStream); 

inputStream = (__bridge NSInputStream *)readStream; 
outputStream = (__bridge NSOutputStream *)writeStream; 

// set the delegates to this view controller 
[inputStream setDelegate:self]; 
[outputStream setDelegate:self]; 

// Set run loops to continuous receive information 
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; 
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; 

// Finally, open the connection 
[inputStream open]; 
[outputStream open];

然后我用下面的处理流事件：

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent { 
    NSLog(@"stream event %i", streamEvent); 

    switch (streamEvent) { 

     case NSStreamEventOpenCompleted: 
      NSLog(@"Stream opened"); 
      break; 

     case NSStreamEventHasBytesAvailable: 
      if (theStream == inputStream) { 

       uint8_t buffer[1024]; 
       int len; 

       while ([inputStream hasBytesAvailable]) { 
        len = [inputStream read:buffer maxLength:sizeof(buffer)]; 
        if (len > 0) { 

         NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding]; 

         if (nil != output) { 
          NSLog(@"server said: %@", output); 
          [self messageReceived:output]; 
         } 
        } 
       } 
      } 
      break; 

     case NSStreamEventErrorOccurred: 
      NSLog(@"Can't connect to server"); 
      break; 

     case NSStreamEventEndEncountered: 
      [theStream close]; 
      [theStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; 
      break; 

     default: 
      NSLog(@"Unknown event"); 
    }

所以，我可以看到，前两个流被正确打开。然后立即跟踪一个流事件4，从我的理解中可以预料到这一点。然而，我再尝试调用一个函数：

- (IBAction)moveForward 
{ 
    NSLog(@"move forward called"); 
    NSString *response = [NSString stringWithFormat:@"2"]; 
    NSData *data = [[NSData alloc] initWithData:[response dataUsingEncoding:NSASCIIStringEncoding]]; 
    [outputStream write:[data bytes] maxLength:[data length]]; 
}

应当从一个Arduino UNO通过wifly返回“前进”。但是，当我点击时，出于某种原因，我得到另一个NSStreamEvent 4。我还通过终端telnetted在将该设备与：

的telnet 169.254.1.1 2000

并随后键入“2” ...这返回所需的“正向”立即。从iPad的角度来看，我做错了什么？

此外，该代码是工作几个星期前。但是一旦我更新了模拟器，它就停止工作......连接正常打开，但是Arduino设备似乎没有从iOS获得输出。

非常感谢帮助！

答

尝试更换的NSString *响应= [NSString的stringWithFormat：@ “2”]; 与此的NSString *响应= [NSString的stringWithFormat：@ “％d”，2]; in moveForward方法。

答

NSStreamEvent 4是NSStreamEventHasSpaceAvailable。在发送数据之前，您必须等到输出流具有可用空间。

IOS socket编程 - NSStream不工作

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