title: Crop zoomed image in UIScrollView issue
body: <p>After going through <a href="https://stackoverflow.com/questions/13784182/objective-c-ios-crop-image-using-zoom">this link</a>, issue with my code is that output image is unable to set proper x and y values as cropped image seems to have 0 and 0 in the resultant image irrespective to where I zoom (or where the scroll offset is calculated). Here's what I tried. </p>
  
  <pre><code>- (IBAction)crop:(id)sender
  {
  
      float zoomScale = 1.0f / [self.scroll zoomScale];
  
      CGRect rect;
      NSLog(@"contentOffset is :%f,%f",[self.scroll contentOffset].x,[self.scroll contentOffset].y);
      rect.origin.x = self.scroll.contentOffset.x * zoomScale;
      rect.origin.y = self.scroll.contentOffset.y * zoomScale;
      rect.size.width = self.scroll.bounds.size.width * zoomScale;
      rect.size.height = self.scroll.bounds.size.height * zoomScale;
  
      UIGraphicsBeginImageContextWithOptions( CGSizeMake(rect.size.width, rect.size.height),
                                             NO,
                                             0.);
  
      NSLog(@"rect offset is :%f,%f",rect.origin.x,rect.origin.y);
      CGPoint point = CGPointMake(-rect.origin.x, -rect.origin.y); **//even though above NSLog have some values, but output image is unable to set proper x and y values as cropped image seems to have 0 and 0 in the resultant image.**
      [[self.imagV image] drawAtPoint:point
                            blendMode:kCGBlendModeCopy
                                alpha:1];
      self.croppedImage = UIGraphicsGetImageFromCurrentImageContext();
  
      UIGraphicsEndImageContext();
  
  DTImageViewController *imageViewController = [[DTImageViewController alloc] initWithNibName:@"DTImageViewController" bundle:nil];
      imageViewController.image = self.croppedImage;
      [self.navigationController pushViewController:imageViewController animated:YES];
  }
  </code></pre>