Has anyone attempted to render a WKWebView in a background or invisible UIView so that it’s visible immediately upon first presentation, and if so, what technique did you use?
Background:
We are trying to embed a WKWebView in our UI that renders seamlessly next to native UI. We are going to download a .ZIP file, unzip it locally to disk, and then point the WKWebView to that local file. However, when testing this solution on an iOS simulator (running iOS 17.5), we see a flash of white – specifically there is no content rendered for the first moment or two, followed by content appearing.
We have tried attaching the WKWebView to the UIWindow, adding a javascript callback for the onReadyStateChange “loaded” event, and then only proceeding to present our UIViewController containing our WKWebView afterwards, but we still see a moment with no content being rendered at all. If we add a delay using DispatchQueue.asyncAfter of approximately one second (anything less still flashes), our content does seem to be correctly rendered in the background and immediately visible when the UIViewController gets presented.
This is a problem that was originally asked nearly 11 years ago (https://stackoverflow.com/questions/15669809/how-to-prevent-initial-white-flash-when-showing-a-uiwebview); and the agreed upon solution there seems to be to set the background to be not opaque, but the issue remains that the content isn’t immediately visible. Google Gemini and ChatGPT have proposed a number of solutions, including hallucinations about headless WKWebView support on iOS, but unfortunately we are unable to achieve a solution without a DispatchQueue delay with a magic number.