title: Cropping UIImage like camscanner
body: <p>I am stuck in my application feature. I want cropping feature similar to Cam Scanner Cropping.
  The screens of CAM-SCANNER are:
   I have created similar crop view.</p>
  
  <p><img src="https://i.stack.imgur.com/ghG6S.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/5P24o.png" alt="enter image description here"></p>
  
  <p><strong>I have obtained CGPoint of four corners.
  But How can I obtained cropped image in slant.</strong></p>
  
  <p>Please provide me some suggestions if possible.</p>