How to check whether WKWebView has cached data available?

Question

I'm trying to implement HTTP caching for a WKWebView that should behave like this:

Network available: Fetch web data from network & cache it.
Network unavailable and has cached data: Load the cached data.
Network unavailable and doesn't have cached data: Show a fallback error view.

First I'm using similar code like in this answer https://stackoverflow.com/a/55909771/356105 to cache data and check if data has been cached. i don't think this should be necessary for use with WKWebView but I couldn't find any better solution to check for cached data.

Then I'm using https://github.com/ashleymills/Reachability.swift to check if a network connection is available at all before trying a web view load request. If no network connection is available but there is cached data found by using downloadContent() I'm trying a web view load after changing the cachePolicy:

    var request = request
    request.cachePolicy = .returnCacheDataDontLoad
    _webView.load(request)

If there is no network and no cached data, I want to show my fallback view:

private func onWebViewNavigationFailed(navigation: WKNavigation!, error: Error)
{
    if !_isNetworkReachable && !_hasChachedData
    {
        showEmptyResultView()
    }
}

But this whole construct is working unreliably. With some web pages it works, with some not. When it has cached data (_hasChachedData = true) half of the time the webview loads the cached data, the other times not at all...

So my question is: What's the proper way to implement caching with WKWebView and how can I check if WKWebView has cached data available for a specific request? There has been a lot of guess work because I cannot find one suitable solution on the web for this.

A rundown on how to implement this requirement properly would be very helpful.

How to check whether WKWebView has cached data available?

0 Answers0