Swift iOS Cache WKWebView content for offline view

I know I'm late, but I have recently been looking for a way to store web pages for offline reading, and still could't find any reliable solution that wouldn't depend on the page itself and wouldn't use the deprecated UIWebView. A lot of people write that one should use the existing HTTP caching, but WebKit seems to do a lot of stuff out-of-process, making it virtually impossible to enforce complete caching (see here or here). However, this question guided me into the right direction. Tinkering with the web archive approach, I found that it's actually quite easy to write your own web archive exporter.

As written in the question, web archives are just plist files, so all it takes is a crawler that extracts the required resources from the HTML page, downloads them all and stores them in a big plist file. This archive file can then later be loaded into the WKWebView via loadFileURL(URL:allowingReadAccessTo:).

I created a demo app that allows archiving from and restoring to a WKWebView using this approach: https://github.com/ernesto-elsaesser/OfflineWebView

EDIT: The archive generation code is now available as standalone Swift package: https://github.com/ernesto-elsaesser/WebArchiver

The implementation only depends on Fuzi for HTML parsing.

I would recommend investigating the feasibility of using App Cache, which is now supported in WKWebView as of iOS 10: https://stackoverflow.com/a/44333359/233602