[rive_native] iOS crash in rive_native_plugin.mm when registerWithRegistrar is called multiple times

[lawinski]

Hi Rive team 👋

I've encountered a crash when using rive_native on iOS in combination with plugins like workmanager or home_widget. These plugins typically use setPluginRegistrantCallback to support multiple FlutterEngine instances (e.g. for background tasks).

This leads to multiple calls to registerWithRegistrar in rive_native_plugin.mm, and ultimately causes a crash:

std::unique_lock<std::mutex> lock(rt->_mutex); // <- EXC_BAD_ACCESS

Each new call to registerWithRegistrar method replaces the existing instance which I guess leads to that issue.

+ (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar
{
    FlutterMethodChannel* channel =
        [FlutterMethodChannel methodChannelWithName:@"rive_native"
                                    binaryMessenger:[registrar messenger]];
    riveNativePluginInstance =
        [[RiveNativePlugin alloc] initWithTextures:[registrar textures]];
    [registrar addMethodCallDelegate:riveNativePluginInstance channel:channel];
}

✅ Possible solution
Adding a guard to prevent reinitialization of the global riveNativePluginInstance solves the crash. However, I haven’t verified if this introduces any side effects in more complex setups. I just wanted to share my findings in case it's helpful or something you’d want to address in the plugin directly.

[HayesGordon]

Thanks for reporting @lawinski, we're also investigating other work related to the plugin initialisation and will take a look at this.

[HayesGordon]

@lawinski, we've made some changes to the global context, and it should have resolved this. Can you confirm on your side that it's working in the latest release v0.0.3

[lawinski]

Great, thanks for the update! I just checked and it looks like the issue is no longer occurring :)

[HayesGordon]

Thanks for confirming and closing the issue!