title: What happens to SDWebImage Cached Images in my app when the image file on the server changes?
body: <p>I am using the <code>SDWebImage</code> library to cache web images in my app:</p>
  
  <p><a href="https://github.com/rs/SDWebImage/blob/master/README.md" rel="noreferrer">https://github.com/rs/SDWebImage/blob/master/README.md</a></p>
  
  <p>Current Usage:</p>
  
  <pre><code>[imageView setImageWithURL:[NSURL URLWithString:profilePictureUrl] placeholderImage:[UIImage imageNamed:@"placeholder.png"]];
  </code></pre>
  
  <p>My question is what happens once the image has been cached and then a couple of days later that image file on the server has been updated with a new image?</p>
  
  <p>At the moment my application is still displaying the cached image.</p>
  
  <p>I can't see in any of the documentation on setting a cache timeout or something that recognises that the file size has changed.</p>
  
  <p>If anyone has experience using this particular library then any help would be greatly appreciated.</p>
  
  <p>Thanks in advance.</p>