c# - 如何让我的应用在加载但未在前台运行时发送通知？

Question

我有一个有时会使用的应用程序。我一定是在睡觉前把它留在了后台。当我醒来时，我在屏幕上看到了这个通知。

有人对我如何在我的XF应用程序中显示这样的通知有任何建议吗？

此外，这些通知是否也会出现在Android上？我从未在我的Android手机上看到过它们，但这可能是因为我使用它的次数少得多。

标签： c#xamarinxamarin.formsxamarin.androidxamarin.ios

Answer 1

我们可以使用Shiny.Notifications NuGet 包在 Xamarin.Forms 中创建跨平台的本地通知

示例应用

可以在此处找到使用以下代码创建的完整示例应用程序：https ://github.com/brminnick/LocalNotificationsSample

演练

1. 安装 Shiny.Notifications

将Shiny.Notifications NuGet 包 v1.2.0.1755添加到 Xamarin.Forms 项目、Xamarin.iOS 项目和 Xamarin.Android 项目。

2. 初始化 Shiny.Notifications

安卓

在[Application]类中OnCreate，通过调用初始化 Shiny Shiny.AndroidShinyHost.Init并通过调用设置其图标Shiny.Notifications.AndroidOptions.DefaultSmallIconResourceName：

using System;
using Android.App;
using Android.Runtime;
using Shiny;

namespace LocalNotificationsSample.Droid
{
    [Application]
    public class YourApplication : Application
    {
        public YourApplication(IntPtr handle, JniHandleOwnership transfer) : base(handle, transfer)
        {
        }

        public override void OnCreate()
        {
            base.OnCreate();
            AndroidShinyHost.Init(this, platformBuild: services => services.UseNotifications());
            Notifications.AndroidOptions.DefaultSmallIconResourceName = "icon.png";
        }
    }
}

在MainActivity.cs, 在OnRequestPermission, 通过添加允许 Shiny 向用户提供请求通知权限Shiny.AndroidShinyHost.OnRequestPermissionsResult(requestCode, permissions, grantResults);

using Android.App;
using Android.Content.PM;
using Android.OS;
using Android.Runtime;

namespace LocalNotificationsSample.Droid
{
    [Activity(Label = "LocalNotificationsSample", Icon = "@mipmap/icon", Theme = "@style/MainTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
            Shiny.AndroidShinyHost.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }

        protected override void OnCreate(Bundle savedInstanceState)
        {
            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;

            base.OnCreate(savedInstanceState);

            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            LoadApplication(new App());
        }
    }
}

iOS

In AppDelegate.cs, in FinishedLaunching, 通过调用初始化 Shiny Shiny.iOSShinyHost.Init:

using Foundation;
using UIKit;
using Shiny;

namespace LocalNotificationsSample.iOS
{
    [Register(nameof(AppDelegate))]
    public partial class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
    {
        public override bool FinishedLaunching(UIApplication app, NSDictionary options)
        {
            iOSShinyHost.Init(platformBuild: services => services.UseNotifications());
            global::Xamarin.Forms.Forms.Init();
            LoadApplication(new App());

            return base.FinishedLaunching(app, options);
        }
    }
}

3. 安排本地通知

在此示例中，我们将立即发送本地通知，并安排在应用启动后一分钟发送通知

using System;
using System.Threading.Tasks;
using Shiny;
using Shiny.Notifications;
using Xamarin.Forms;

namespace LocalNotificationsSample
{
    public partial class App : Application
    {
        public App()
        {
            InitializeComponent();

            MainPage = new MainPage();
        }

        protected override async void OnStart()
        {
            await SendNotificationNow();
            await ScheduleLocalNotification(DateTimeOffset.UtcNow.AddMinutes(1));
        }

        Task SendNotificationNow()
        {
            var notification = new Notification
            {
                Title = "Testing Local Notifications",
                Message = "It's working",
            };

            return ShinyHost.Resolve<INotificationManager>().RequestAccessAndSend(notification);
        }

        Task ScheduleLocalNotification(DateTimeOffset scheduledTime)
        {
            var notification = new Notification
            {
                Title = "Testing Local Notifications",
                Message = "It's working",
                ScheduleDate = scheduledTime
            };

            return ShinyHost.Resolve<INotificationManager>().Send(notification);
        }
    }
}

https://github.com/brminnick/LocalNotificationsSample