Catalyst Release Notes Support

[Vortec4800]

Can I use Sparkle to auto-update apps (distributed outside of the Mac App Store of course) that are built using Catalyst? Is there anything I need to do special to make it all work?

[kornelski]

I haven't tried Catalyst. If it's compatible with Cocoa and can use frameworks, it should be able to use Sparkle.

[samdeane]

Sparkle builds against the normal macOS sdk, so I'm pretty sure you can't use it directly from a Catalyst app.

You can probably use it by bridging to macOS via a plugin, and having the plugin link against Sparkle and create the SUUpdater object.

I'm not sure how well this will work, but I'm planning to try it. Will let you know... :)

[samdeane]

Update: I think the approach I described above should work, but I've currently hit an issue.

My bridging plugin links to Sparkle, embeds the framework, and owns an SPUStandardUpdaterController object. It sets itself to be the updaterDelegate.

The various SU keys are in the main application's Info.plist, as usual.

Checking for updating appears to be working fine.

However, currently, when it finds an update, I'm getting a crash in [SPUStandardUserDriver setUpFocusForActiveUpdateAlert], calling [self.activeUpdateAlert window].

It seems that the system is actually crashing inside WebView, trying to access the alert's window:

As yet, I haven't figured out what's going on here.

[samdeane]

I did wonder if this was something to do with WebView being deprecated on 10.15, and the system log is showing

2020-02-26 14:29:30.695271+0000 Action Status[14298:327670] -[WebView initWithCoder:]: unrecognized selector sent to instance 0x7b180006e1c0

which looks suspiciously like WebView itself isn't there.

However, I've tried swapping out WebView for WKWebView, and I'm still getting a crash in a similar place, so I don't think it's that.

[samdeane]

This crash seems to be related to using WebKit from the bridging plugin, and not specifically anything to do with Sparkle. I suspect that it may be caused by WebKit getting confused about whether or not it's running under AppKit or Catalyst.

Unfortunately WebKit is used by the default driver (via SUUpdateAlert), so it may be necessary to write an alternative driver.

[kornelski]

Does it help if you hide release notes?

[samdeane]

So, I didn't try the hiding of release notes, but I suspect that it wouldn't help.

The WebView would still be in the xib, and just opening a xib-based window containing a WebView from the AppKit side of things is enough to crash.

However, I have got it working: https://twitter.com/samdeane/status/1233081407947395074

The approach I took required a bit of effort, but it allows me to present a custom Sparkle UI from the Catalyst side of things (as it happens I'm using SwiftUI for this, though it's not required).

To do this I had to create a custom Sparkle user driver (implementing the SPUUserDriver protocol), and have it forward all communication over to the Catalyst application.

The details are probably too much to go into here, but I will write it up as a blog post and drop a link here when I'm done.

[samdeane]

I've not yet had time to write that blog post, but I have managed to generalise the code a bit and extract it into an example which you can find here.

[samdeane]

FWIW I updated generalised my code a bit more and made a fairly self-contained solution.

You just link to the framework from your Catalyst app, and it deals with embedding Sparkle and loading the plugin.

[tfonfara]

@kornelski I've also tested a bit, unfortunately hiding the release notes doesn't help as @samdeane already expected because the nib still contains the class.
But if I just remove the class from the xib everything works fine (without release notes but that's okay). Would it be possible to not instantiate the webview from the interface file but adding it from code with a "class exists" check?

[tfonfara]

Another idea: I just noticed this marker:
WEBKIT_CLASS_DEPRECATED_MAC(10_3, 10_14, "No longer supported; please adopt WKWebView.")
If WKWebView would be supported this issue would be solved automatically 😊

[kornelski]

WKWebView requires macOS 10.10+. I've only very recently raised minimum macOS version for Sparkle to 10.9.

[tfonfara]

Got it, what about a if ([WebView class]) { ... } or if (NSClassFromString(@"WebView")) { ... } check? 🤔 Like

if ([WebView class]) {
    WebView webView = [[[WebView] alloc] initWithFrame: [containerView bounds]];
    // set autoresizingMasks
    [containerView addSubview: webView];
} else {
    // set showsReleaseNotes to false to prevent crashes
}

[kornelski]

I know some apps use release notes to warn that an update is not free, so hiding release notes could be an unpleasant surprise.

[kornelski]

Maybe it would be fine to switch Sparkle 2.x only?