title: Can be located which floor we are via smart phone GPS?
body: <p>Is there a way that can decide which floor we are via smart phone?</p>
  
  <p>For example, i m in a building. floor 5;</p>
  
  <p>the native app in my smart phone can know i m on floor 5 and give me some advice about floor 5（navigation to floor 1）</p>