Question

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

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

以下是实施方案：

[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)上显示错误为：

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

我明白这个问题。 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上调，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 Constructor？

编辑：感谢您的帮助。它正在工作，但通知没有显示只有声音正在工作。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");
        }
    }
}

使用Xamarin表单进行本地推送通知

1 个答案: