title: How to correctly implement didReceiveWriteRequests? iOS6 CoreBluetooth
body: <p>I implement iOS CoreBluetooth client &amp; server for sending data</p>
  
  <pre><code>client site
  [self.connectedPeripheral writeValue:mainData forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
  </code></pre>
  
  <p>and</p>
  
  <pre><code>- (void)peripheral:(CBPeripheral *)peripheral didWriteValueForCharacteristic:(CBCharacteristic *)characteristic 
  {
     NSString *s= [[NSString alloc] initWithData:characteristic.value encoding:NSUTF8StringEncoding];
     NSLog(@"didWriteValue characteristic.value: %@ ", s);
  } 
  </code></pre>
  
  <p>and server site</p>
  
  <pre><code>- (void)peripheralManager:(CBPeripheralManager *)peripheral didReceiveWriteRequests:(NSArray *)requests
  {
    NSData *res= [[NSString stringWithFormat:@"Hello"] dataUsingEncoding:NSUTF8StringEncoding];
   [self.peripheral updateValue:res
                          forCharacteristic:self.writeCharacteristic
                       onSubscribedCentrals:nil];
   [peripheral respondToRequest:aReq withResult:CBATTErrorSuccess];
  }
  </code></pre>
  
  <p>however, client can't receive any data. 
  Any idea?
  Thanks for your help. </p>