title: IOS disable the touch area on top of Tab bar
body: <p>The red color area is the area that is always "on top", thus it gets all my touches on the screen.</p>
  
  <p><img src="https://i.stack.imgur.com/uXvTC.png" alt=""></p>
  
  <p>I found that tab bar has such an area that's always on top, and so that blocks all my touch events. Even if I programmatically add a UI button on top of the tab bar items, it also doesn't work.</p>
  
  <p>So, what is it? And how can I remove such area?</p>