title: How to implement floating button in react-native that sticks to the screen at some point of scrolling?
body: <p>I managed to implement floating button by defining button outside of ScrollView, using <code>position: 'absolute'</code> and <code>bottom: 20</code>.</p>
  <p>Now I need this button to stick to the screen when I pass some point during scrolling.</p>
  <p>I don't want it to always float, at some point I want it to stick to the screen. How could I achieve this effect? I saw that in one of the mobile apps and really liked it.</p>