title: CoreBluetooth didWriteValueForCharacteristic returning an old value
body: <p>After connecting to a bluetooth device, I'm trying to write a value to a characteristic by calling:</p>
  
  <pre><code>[peripheral writeValue:data forCharacteristic:characteristic type:CBCharacteristicWriteWithResponse];
  </code></pre>
  
  <p>The right callback is getting called (peripheral:didWriteValueForCharacteristic:error:) but when I look at the data from the characteristic, it seems that the old data is persisting in characteristic.value. However, when I disconnect and reconnect to the device, the new data shows up. This only occurs on iOS 7.</p>
  
  <p>Is there something I may be missing when I send the call out to the peripheral?</p>