Turbolinks-ios: Metadata from web->native

Question

I'm using Turbolinks 5 on the backend, and turbolinks-ios in my iOS app.

When a page loads in a VisitableViewController, I'd like to have the native app receive (or retrieve?) some metadata from the web page, in order to offer some additional UI affordances using native code.

I know I can do this in a roundabout way by setting some <meta> tags on the server side, and then executing JS in the WKWebView and getting at the meta tags that way, but it seems like a hack.

Another option is executing a turbolinks callback message and receiving via addScriptMessageHandler, but that also seems like a hack.

Any help would be appreciated! Perhaps there is a better, sanctioned way to do this? It seems like it would be a common need.

Answer 1

I ended up going with my original idea with the meta tags. Then, what I do is on page load, invoke a message handler like so, passing the contents of those (filtered) meta tags to the handler:

$(function() {
  if (typeof webkit != 'undefined') {
    var metadata = {};
    $('meta[data-scanner-app="true"]').each(function() {
      metadata[$(this).attr('property')] = $(this).attr('content');
    });
    webkit.messageHandlers.ScannerApp.postMessage(metadata);
  }
});

Then I simply intercept that handler in turbolinks, and I have the data.

Note: data-scanner-app is a data attribute I add to just the meta tags I want to include.