title: In iOS, how do I create a button that is always on top of all other view controllers?
body: <p>No matter if modals are presented or the user performs any type of segue.</p>
  
  <p>Is there a way to keep the button "always on top" (not the top of the screen) throughout the entire app?</p>
  
  <p>Is there any way to make this button draggable and snappable to the screen?</p>
  
  <p>I'm looking at Apple's own Assistive Touch as an example of such button.</p>