EPUBNavigatorDelegate method navigator(_:setupUserScripts:) not being called

[russgrav]

Hi all, I'm developing an EPUB reader app using SwiftUI and the Readium Swift Toolkit (latest stable release: 3.2.0). My goal is to inject custom JavaScript into the EPUB navigator's web view to handle word selection for a Japanese dictionary lookup feature (note, I tried using VisualNavigator's didTapAt functionality, but I couldn't figure out how to reliably map the tap gesture coordinates on the screen to the WebView).

I'm trying to use the standard mechanism provided by EPUBNavigatorDelegate: the navigator(_:setupUserScripts userContentController: WKUserContentController) method. However, despite extensive troubleshooting, this specific delegate method is never being called.

I've confirmed that:

1. The EPUBNavigatorViewController's delegate property IS being successfully assigned to my Coordinator instance within the makeUIViewController method of my UIViewControllerRepresentable. Logs confirm the assignment happens and both the navigator and coordinator instances are valid at that point.
2. Other methods defined in EPUBNavigatorDelegate (specifically navigator(_:locationDidChange:)) ARE being called correctly when I navigate the publication. This confirms the fundamental delegate connection is established.
3. My Coordinator conforms to EPUBNavigatorDelegate and implements the navigator(_:setupUserScripts:) method (with logging inside, which never appears).

In terms of troubleshooting, I've:

• Added extensive logging inside navigator(_:setupUserScripts:) - the logs never print.
• Tested with multiple different EPUB files – the issue persists.
• Used the default EPUBNavigatorViewController.Configuration() during initialization.
• Attempted manual injection using evaluateJavaScript after the first locationDidChange. This did execute the JS but failed with TypeError: window.R2NAVIGATOR_SEND_MESSAGE is not a function, indicating the Readium JS bridge wasn't set up at that point (likely because the proper setup phase involving setupUserScripts was skipped, though I'm admittedly not 100% sure about this).

My question is, given that the delegate is correctly assigned and other delegate methods are functioning, why might the navigator(_:setupUserScripts:) method specifically not be called during the EPUBNavigatorViewController's setup? Are there known conditions, configurations, or specific timing issues related to the internal PaginationView or EPUBSpreadView creation that could cause this hook to be skipped?

Is there an alternative, reliable way within the Readium framework to inject WKUserScripts or otherwise execute custom JavaScript reliably before the EPUB content fully loads its own scripts, if setupUserScripts proves unreliable in my case?

Any insights or suggestions would be greatly appreciated! Thanks.

Environment:
Readium Swift Toolkit Version: 3.2.0
Xcode Version: 16.3
Target OS: iOS 18.0

[mickael-menu]

Hello, did you find a solution to your issue or you still need help?