SPUUpdaterDelegate feedURLString not working

[Alec-4Privacy]

Sparkle is working fine when I define feedUrl in plist but is not working when I define it using SPUUpdaterDelegate.feedURLString, it gives me an error modal that says: "You must specify the URL of the appcast as the SUFeedURL key in either the Info.plist, or with -[SPUUpdaterDelegate feedURLStringForUpdater:]" but I am specifying the feedUrl using SPUUpdaterDelegate.feedURLString

Do you use Sandboxing in your app? No.

Version of Sparkle.framework in the latest version of your app: 2.4.1

Version of Sparkle.framework in the old version of app that your users have: N/A

Sparkle's output from Console.app

Error: You must specify the URL of the appcast as the SUFeedURL key in either the Info.plist, or with -[SPUUpdaterDelegate feedURLStringForUpdater:] for app! (null) (URL (null))

Steps to reproduce the behavior

The application is a flutter application but I am not sure that matters. In the MacOS swift project, we have added the Sparkle framework via pods.

AppDelegate looks like this:
`
class AppDelegate: FlutterAppDelegate {
let updaterController: SPUStandardUpdaterController

override func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
    return true
}

override init() {
    updaterController = SPUStandardUpdaterController(startingUpdater: true, updaterDelegate: CustomSPUUpdaterDelegate(), userDriverDelegate: nil)
}

override func applicationDidFinishLaunching(_ aNotification: Notification) {
    
    //Register for platform-specific method handler
    let controller : FlutterViewController = mainFlutterWindow?.contentViewController as! FlutterViewController
    
    let sparkleChannel = FlutterMethodChannel.init(name: "com.app/sparkle", binaryMessenger: controller.engine.binaryMessenger)
    sparkleChannel.setMethodCallHandler({
        (call: FlutterMethodCall, result: @escaping FlutterResult) -> Void in
        if call.method == "launchUpdaterUI" {
            self.updaterController.checkForUpdates(nil);
            result(nil);
        } else {
            result(FlutterMethodNotImplemented)
        }
    })
    
    super.applicationDidFinishLaunching(aNotification)
}

}

`

CustomSPUUpdaterDelegate is as simple as it can get, it just returns a hardcoded string. We want to do more here but just testing the simplest scenario.

class CustomSPUUpdaterDelegate: NSObject, SPUUpdaterDelegate { func feedURLString(for updater: SPUUpdater) -> String? { return "https://app.blob.core.windows.net/artifacts/dev/appcast.xml"; } }

[zorgiepoo]

One issue I see is your AppDelegate needs to keep the CustomSPUUpdaterDelegate alive as a property or instance variable. The updater weakly references it and doesn't strongly retain it.