title: on tap of background change the background color to selected color
body: <p><img src="https://i.stack.imgur.com/ailFm.png" alt="enter image description here"></p>
  
  <p>i want to add one functionality in my app like user can change the color of similar portion of background color where he touch.also user can undo the events, there is one application called <strong><a href="https://itunes.apple.com/us/app/wall-painter/id396799182?mt=8" rel="nofollow noreferrer">wall Pentair</a></strong> i exact want same functionality.</p>
  
  <p>i don't know where to start it, which frameworks have to use for it.</p>
  
  <p>I would highly appreciate any help with this please.</p>