c# - 使用 Xamarin Forms 的本地推送通知

Question

我正在尝试使用 DependencyService for Xamarin Forms 实现本地推送通知。这里的界面:

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

这里是andriod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:

Cannot Convert from 'TestMVVM.Droid.NotificationService' to '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，以及对应用程序级操作的向上调用，例如启动事件、广播和接收意图等(引用: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，但通知并没有显示只有声音在工作。这里的代码:

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");
        }
    }
}