title: Get back original size (height, width) from UIImage load with imageWithData
body: <p>I just cant find useful information from web.</p>
  
  <p>I have an UIImage which loaded from sqlLite with method imageWithData(NSData*), I just find the height and width of the size both be zero. I wanna get back the original height and width of the image, is it possible? or I do need to store these information separately in sqllite?</p>