title: Scroll textview when selecting text cover whole textview's screen area
body: <p>In my application there is one UIScrollView having UITextView.  </p>
  
  <p>if the UITextView has 200 lines and user will select the first line and <strong>drag the last end point of selected text</strong> and user will drag that point to select more lines.  </p>
  
  <p>then, in a screen whatever the text seen, the user can select but the scroll view isn't <strong>automatic scrolling to</strong> select <strong>another text line</strong>.  </p>
  
  <p>may be it's quite confusing to understand but i don't know exactly what to ask for this question.  </p>
  
  <p>for understanding i am putting image here. in image that blue colored last end point will drag down then UITextView should scroll. that functionality i want in my application.  </p>
  
  <p><img src="https://i.stack.imgur.com/QlymF.png" alt="enter image description here"></p>
  
  <p>any types of idea, code,link will be great help...</p>
  
  <p><strong>EDIT :</strong>  </p>
  
  <p>The text view is fit to 200 lines.<br>
  means the text height is that much that 200 lines of text having.<br>
  so i have to scroll the scroll view and for that need any event will call on drag down the end point.</p>