使用 Xamarin 表单的本地推送通知

Question

我正在尝试使用 Xamarin 表单的 DependencyService 实现本地推送通知。 这里是界面：

public interface INotification
    {
        void SetNotification(DateTime notificationDate, TimeSpan notificationTime);
    }

这里是安卓的实现：

[assembly:Dependency(typeof(NotificationService))]
namespace TestMVVM.Droid
{
    public class NotificationService : INotification
    {
        public void SetNotification(DateTime notificationDate, TimeSpan notificationTime)
        {
            Notification.Builder builder = new Notification.Builder(this)
                .SetContentTitle("Test Notification")
                .SetContentText("Notification from Xamarin Forms");
        }
    }
} 

它在Notification.Builder builder = new Notification.Builder(this) 上显示错误：

无法从“TestMVVM.Droid.NotificationService”转换为 'Andriod.Content.Context'

我确实理解这个问题。 Context 允许访问特定于应用程序的资源和类，以及向上调用应用程序级操作，例如启动活动、广播和接收意图等（请参阅：https://developer.xamarin.com/api/type/Android.Content.Context/#Remarks）。由于它是一个抽象类，我无法创建对象并将其传递给Builder 的构造函数。 如何将上下文传递给 Builder 构造函数？

编辑：感谢您的帮助。它正在工作，但通知不仅显示声音正在工作。这里是代码：

Notification.Builder builder = new Notification.Builder(Xamarin.Forms.Forms.Context)
                .SetContentTitle("Test Notification")
                .SetContentText("Notification from Xamarin Forms")
                .SetDefaults(NotificationDefaults.Sound)
                .SetWhen(Java.Lang.JavaSystem.CurrentTimeMillis());

            Notification notification = builder.Build();
            NotificationManager notificationManager =
                                        Forms.Context.GetSystemService(Context.NotificationService) as NotificationManager;
            const int notificationId = 0;
            notificationManager.Notify(notificationId, notification);

Answer 1

使用Xamarin.Forms.Forms.Context

[assembly:Dependency(typeof(NotificationService))]
namespace TestMVVM.Droid
{
    public class NotificationService : INotification
    {
        public void SetNotification(DateTime notificationDate, TimeSpan notificationTime)
        {
            Notification.Builder builder = new Notification.Builder (Xamarin.Forms.Forms.Context)
                .SetContentTitle ("Test Notification")
                .SetSmallIcon(Android.Resource.Drawable.AlertDarkFrame)
                .SetWhen (Java.Lang.JavaSystem.CurrentTimeMillis ())
                .SetDefaults (NotificationDefaults.Sound)
                .SetContentText ("Notification from Xamarin Forms");
        }
    }
}