Xamarin跨平台应用：Android/iOS图标角标显示及iOS模拟器问题求助

Hey Srinivas, let's walk through some common fixes to get your app icon badge showing up in the iOS simulator:

1. Don't Skip Plugin Initialization #

Most Xamarin plugins need a native platform initialization step, and this is easy to miss! In your iOS project's AppDelegate.cs, make sure you call the plugin's init method before trying to set the badge:

public override bool FinishedLaunching(UIApplication app, NSDictionary options)
{
    // Initialize the badge plugin first
    CrossBadge.Current.Init();
    
    // Test with a hardcoded number to rule out timing issues
    CrossBadge.Current.SetBadge(3);
    
    // Rest of your FinishedLaunching logic...
    return base.FinishedLaunching(app, options);
}

Without this initialization, the plugin can't hook into iOS's native badge APIs properly.

2. Make Sure Notification Permissions Are Granted #

iOS requires explicit user permission to show badges (along with alerts and sounds). Add this code to request the right permissions early in your app's lifecycle:

using UserNotifications;

// Inside FinishedLaunching or a dedicated startup method
var notificationCenter = UNUserNotificationCenter.Current;
notificationCenter.RequestAuthorization(UNAuthorizationOptions.Badge | UNAuthorizationOptions.Alert | UNAuthorizationOptions.Sound, (granted, error) =>
{
    if (granted)
    {
        Console.WriteLine("Permissions granted - badges should work!");
    }
    else
    {
        Console.WriteLine("Permissions denied - check app settings.");
    }
});
UIApplication.SharedApplication.RegisterForRemoteNotifications();

When you launch the app, tap "Allow" on the permission prompt. If you accidentally denied it, go to Settings -> [Your App] -> Notifications and toggle on "Badge App Icon".

3. Check Simulator-Specific Settings #

Simulators can have quirky caching or disabled settings:

• Open the iOS simulator, go to Settings -> Notifications -> [Your App Name]
• Double-check that the Badge App Icon toggle is switched on
• Try restarting both the simulator and your app—sometimes a fresh start fixes delayed badge updates

4. Rule Out Plugin Issues with Native Code #

To test if the problem is with the plugin itself, replace your plugin call with native iOS code:

UIApplication.SharedApplication.ApplicationIconBadgeNumber = 5;

If this works, the issue is likely with the Xam.Plugin.Badge (try updating it to the latest version via NuGet). If it doesn't work, the problem is tied to permissions or simulator configuration.

5. Update Dependencies #

Outdated versions of the plugin or Xamarin.iOS SDK can cause compatibility bugs. Open NuGet Package Manager in Visual Studio, update Xam.Plugin.Badge to the latest version, and ensure your Xamarin.iOS tools are up to date.

内容的提问来源于stack exchange，提问作者srinivas challa