title: setBackgroundimage in UIButton using SDWebimage
body: <p>I want to set the UIButton background image using SDWebImage.</p>
  
  <p>Code :- </p>
  
  <pre><code>[btn.imageView setImageWithURL:[NSURL URLWithString:@"image url here"]
                             placeholderImage:[UIImage imageNamed:@"placeholder"]];
  </code></pre>
  
  <p>Thanks</p>