@Max – thanks for the kind words.
When Brett Terpstra and I decided to work on nvUltra (https://nvultra.com/), one of the decisions we had to make was WKWebView vs WebView. At the time I did not know about the April 2020 deadline (I don’t believe it had been announced at that point, but who knows…) I had previously looked at WKWebView for Composer and I couldn’t get it to work.
We were unable to get WKWebView to properly preview HTML that relied on local files (e.g. images). Remote images (e.g. on http server) worked, but not local files. The workaround we finally used was to run an embedded http server as a proxy. Not ideal, but it does work. This seems to be a bug between WKWebView/sandboxing, rather than an intentional decision by Apple since I couldn’t find any documentation of this, but it could very well have been doing something wrong on our parts. My hope is that we will be able to move away from the web server at some point, but it is not a deal breaker. I have not retested this since the spring, so the situation may have already changed.
We were unable to get printing to work successfully from WKWebView, and the last time I searched many others struggled with the same thing. This would seem to be an oversight and hopefully will be fixed by the time WebView is finally killed off?? Our workaround here was to send the user to their browser, and then print from the browser if a user wants to print the preview. This is certainly less than ideal, but does work…
As development on nvUltra 1.0 is wrapping up, I will then work on migrating the changes back into Composer (I have intentionally factored the code in such a way as to keep the core components identical to allow me to fix bugs once across both apps, rather than doing the same work twice. And most of the code is also written to be compatible with iOS as well, so I can continue to try and get an iOS text editor built that I am happy with. The latest beta of MultiMarkdown Composer for iOS was close, but there were some issues with Spotlight search on iOS that sent me down the nvUltra rabbit hole when I wrote my own text file indexing algorithm…)
So the shorter answer is that Composer will be modified to use WKWebView, and hopefully the few remaining issues with WKWebView will be solved. But if not, I at least have workarounds for the pieces of WKWebView that are broken, even if they are ugly workarounds.