Debugging our offline applications is extremely important, after all, if our application depends on network connectivity, it’s crucial we deliver an alternative experience that is successful to our users. However, it is not easy to debug an offline application. There are several reasons for this, but it’s mostly based on the implementation of the application cache interface.
When Safari revisits your site, the site is loaded from the cache. If the cache manifest has changed, Safari checks the HTML file that declares the cache, as well as each resource listed in the manifest, to see if any of them has changed.
A file is considered unchanged if it is byte-for-byte identical to the previous version; changing the modification date of a file does not trigger an update. You must change the contents of the file. (Changing a comment is sufficient.)
This can be found in the Apple documentation at: https://developer.apple.com/library/safari/#documentation/iPhone/Conceptual...