title: How to resize SDWebImage before Cache, considering UIImageView size
body: <p>I am using SDWebImage to load and cache Images I am loading into my tableViewCells. I want to resize the images in order to get better scrolling performance and wrote a resize function as extension to UIImageView, that resizes the images to the size of its imageView. Searching for a solution I found the SDWebImageManager function that can be used to resize an Image before caching it, the only problem is that the parameter is a UIImage, so I can't resize it to fit the ImageView it is in. I hope you guys got what I mean. That's how I am doing it at the moment, which is kinda bad for performance, cause it gets resized every time the cell is displayed. size is the size of the ImageView of course.</p>
  
  <pre><code>cell.firstImage.sd_setImage(with: URL(string: image0Uri), completed: { (img, err, cache, url) in
                      cell.firstImage.resize(toSize: size)
                  })
  </code></pre>