Erica Sadun's UIView-Transform category http://www.informit.com/articles/article.aspx?p=1951182

ui_view_additions.rb

module UIViewAdditions
  def offsetPointToParentCoordinates(aPoint)
    CGPointMake(aPoint.x + center.x, aPoint.y + center.y)
  end

  def pointInViewCenterTerms(aPoint)
    CGPointMake(aPoint.x - center.x, aPoint.y - center.y)
  end

  def pointInTransformedView(aPoint)
    offsetItem  = pointInViewCenterTerms(aPoint)
    updatedItem = CGPointApplyAffineTransform(offsetItem, transform)
    finalItem   = offsetPointToParentCoordinates(updatedItem)

    finalItem
  end

  def originalFrame
    currentTransform = transform
    self.transform = CGAffineTransformIdentity
    originalFrame = frame
    self.transform = currentTransform

    originalFrame
  end

  def transformedTopLeft
    frame = originalFrame
    point = frame.origin

    pointInTransformedView(point)
  end

  def transformedTopRight
    frame = originalFrame
    point = frame.origin
    point.x += frame.size.width

    pointInTransformedView(point)
  end

  def transformedBottomRight
    frame = originalFrame
    point = frame.origin
    point.x += frame.size.width
    point.y += frame.size.height

    pointInTransformedView(point)
  end

  def transformedBottomLeft
    frame = originalFrame
    point = frame.origin
    point.y += frame.size.height

    pointInTransformedView(point)
  end
end

UIView.send(:include, UIViewAdditions)