title: How can I know if my device's blue tooth is power on?
body: <p>I just need to get my ios device's bluetooth state.</p>
  
  <p>Is there somebody know the API,I have search for the apple.com but didn't found sth, also I know I can use the <code>CoreBluetooth</code>,but it can just be used when <code>IOS6</code> later,so what about <code>IOS5</code>?</p>