title: Drag up Child View Controller with finger and lock after point
body: <p>I'm trying to implement a smooth transition between two view controllers. What I want to do is have a UIView on the bottom of VC 1. When a user swipes/drags the view upwards, VC 2 will be modally presented. What I want to have happen is as the user drags the view upwards, the view will follow the finger and VC 2 will be dragged onto the screen. As soon as the users finger has gone past a point and then been released, I want it to then lock in place.</p>
  
  <p>I have successfully implemented a UIGestureRecognizer for when a user swipes up on the view. It then presents. There are only two problems with this:</p>
  
  <p>1) It does not transition with the user's finger
  2) There are only 4 modal transition styles (Cover Vertical, Flip Horizontal, Cross Dissolve and Partial Curl) - none of which I want to use. I want it to slide up.</p>
  
  <p>I have researched and found this question <a href="https://stackoverflow.com/questions/17162849/how-to-swipe-down-a-uiviewcontroller-from-another">How to swipe down a UIViewController from another</a> however it hasn't helped as it presents a UIView rather than a UIViewController!</p>
  
  <p>If anyone has any suggestions or example bits of code form someone who has done this before that would be great! </p>
  
  <p>Thank you!</p>