Respect Header Cache Age From URL

[bassrock]

Things like Facebook Images have header cache ages. It would be cool if this library automatically handled it much like https://github.com/rs/SDWebImage does on iOS.

[nostra13]

This feature will be included into the library faster if you provide some additional info about concrete headers, their format, etc. Or create pull request with solution.

[bassrock]

So basically iOS can be told to listen to the server's cache headers. So with Facebook Images there is a header that looks like this:

ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"

I am not sure how android handles this internally. But basically the basic functionality explanation is, if there is a cached image then use that and try to redownload the latest image in the background. This is useful for Facebook profile pictures as they are usually constantly changing.