[Xamarin.Forms] Open App Settings

Droid.SettingsHelper.cs

public class SettingsHelper
{
    public void OpenAppSettings()
    {
        var intent = new Intent(Android.Provider.Settings.ActionApplicationDetailsSettings);
        intent.AddFlags(ActivityFlags.NewTask);
        var uri = Android.Net.Uri.FromParts("package", package_name, null);
        intent.SetData(uri);
        Application.Context.StartActivity(intent);
    }
}

iOS.SettingsHelper.cs

public class SettingsHelper
{
    public void OpenAppSettings()
    {
        var url = new NSUrl($"app-settings:{app_bundle_id}");
        UIApplication.SharedApplication.OpenUrl(url);
    }
}

ISettingsHelper.cs

public interface ISettingsHelper
{
    void OpenAppSettings();
}