如何使用 Firebase 在 Xamarin 中实现推送通知和使用 C# 后端的 Apple 推送通知 [英] How to implement Push Notification in Xamarin with Firebase and Apple Push Notification with C# backend

问题描述

在我从原生 Android 和 iOS 迁移到 Xamarin.Forms 期间，我决定使用 AppCenter Push 作为我的通知，因为它是免费且易于使用的(当然，我花了很多时间让它工作，因为这是相对较新的事物，在线指导较少).您可以在 如何实现 AppCenter Push API?.

During my migration from Native Android and iOS to Xamarin.Forms, I had decided to use AppCenter Push for my notification, since it is free and easy to use (of course I spent a good amount of time to make it works since it's relatively new thing with less guidance online). You can find my original sharing at How to implement AppCenter Push API?.

我对此很满意，直到 Microsoft 宣布将停用 AppCenter Push (https://devblogs.microsoft.com/appcenter/app-center-mbaas-retirement/) 并鼓励用户迁移到 Azure(这是一项付费服务​​).我决定改回使用原生 FCM 和 APN 来发送我的推送通知.

I was happy with it until Microsoft announced that it is retiring AppCenter Push (https://devblogs.microsoft.com/appcenter/app-center-mbaas-retirement/) and encouraged user to move over to Azure (which is a paid service). I decided to move back to use the native FCM and APN for my push notification.

问题是没有关于如何完成整个事情的直接教程.有问题&当我的项目在不受支持的 .Net Framework 上运行时，这里和那里的解决方案(例如 iOS .P8 仅适用于 HTTP/2).只有 .Net Core 可以支持 HTTP/2 协议.

The problem is there is no direct tutorials on how to do the entire thing. There are problems & solutions here and there such as iOS .P8 only works on HTTP/2 while my project is running on .Net Framework which is not supported. Only .Net Core could HTTP/2 protocol.

推荐答案

我当前的项目在 ASP.NET C# 上运行作为后端，它使用 Xamarin.Forms 向 Xamarin.Android 和 Xamarin.iOS 发送通知.如果您像我一样，请在下面找到我的答案，我将在下面分享完全可用的 C# 后端和 Xamarin.Forms 解决方案.让更多的用户可以从免费服务中受益，而不是被推送到 Azure 付费服务.

My current project runs on ASP.NET C# as the backend, which send notification to Xamarin.Android and Xamarin.iOS using Xamarin.Forms. If you're like me, please find my answer below, I am sharing the fully working C# backend and Xamarin.Forms solution below. So that more user can benefit from FREE service instead of being pushed to Azure paid service.

第 1 部分 C# 后端 - C# ASP.NET 后端.它将分为 2 部分，分别用于 FCM 和 APN.

PART 1 C# Backend - The C# ASP.NET backend. It will be split to 2 parts, for FCM and APNs.

1.1) Firebase (FCM)

1. 要设置 FCM，您需要注册一个帐户.网上有很多指南，这是一个很好的指南 https://xmonkeys360.com/2019/12/08/xamarin-forms-fcm-setup-configuration-part-i/.请记住获取服务器密钥并将 google-services.json 文件下载到您的 Xamarin.Android 项目.右键单击并将构建操作设置为GoogleServiceJson"；(我在哪里可以在 xamarin 中添加 google-services.json应用).

1. To setup FCM, you'll need to register an account. There are tonnes of guideline online, this is one of the good one https://xmonkeys360.com/2019/12/08/xamarin-forms-fcm-setup-configuration-part-i/. Remember to get the Server Key and download the google-services.json file to your Xamarin.Android project. Right-click and set the build action to "GoogleServiceJson" (Where can i add google-services.json in xamarin app).

下面是我的 Firebase

Below is my Firebase

using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.IO;
using System.Net;
using System.Web.Script.Serialization;

namespace PushNotificationLibrary
{
    public class FirebaseCloudMessagingPush
    {
        private const string WEB_ADDRESS = "https://fcm.googleapis.com/fcm/send";

        private const string SENDER_ID = "YOUR SENDER ID";
        private const string SERVER_KEY = "YOUR SERVER KEY";

        public string SendNotification(string deviceToken, string title, string message, string priority = "high", int badge = 0, List<Tuple<string, string>> parameters = null)
        {
            var result = "-1";
            var httpWebRequest = (HttpWebRequest)WebRequest.Create(WEB_ADDRESS);

            parameters = parameters ?? new List<Tuple<string, string>>();

            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Headers.Add(string.Format("Authorization: key={0}", SERVER_KEY));
            httpWebRequest.Headers.Add(string.Format("Sender: id={0}", SENDER_ID));
            httpWebRequest.Method = "POST";

            if (title.Length > 100)
                title = title.Substring(0, 95) + "...";

            //Message cannot exceed 100
            if (message.Length > 100)
                message = message.Substring(0, 95) + "...";

            JObject jObject = new JObject();
            jObject.Add("to", deviceToken);
            jObject.Add("priority", priority);
            jObject.Add("content_available", true);

            JObject jObjNotification = new JObject();
            jObjNotification.Add("body", message);
            jObjNotification.Add("title", title);            

            jObject.Add("notification", jObjNotification);

            JObject jObjData = new JObject();

            jObjData.Add("badge", badge);
            jObjData.Add("body", message);
            jObjData.Add("title", title);

            foreach (Tuple<string, string> parameter in parameters)
            {
                jObjData.Add(parameter.Item1, parameter.Item2);
            }

            jObject.Add("data", jObjData);

            var serializer = new JavaScriptSerializer();
            using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
            {
                string json = jObject.ToString();
                streamWriter.Write(json);
                streamWriter.Flush();
            }

            var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                result = streamReader.ReadToEnd();
            }

            return result;
        }
    }
}

1.2) iOS (APN)

1. 对于 APN，有两种处理方式.一种是使用.P12 常规方式.另一种方法是使用 .P8 使用 Apple Auth Keys.我更喜欢使用 .P8，因为 .P12 证书每年都会过期，需要每年更新.使用 .P8 的问题在于，它使用的是 .Net Framework 不支持的 HTTP/2，但幸运的是，我设法克服了这个问题.请参考 如何在 C# 中实现基于苹果令牌的推送通知(使用 p8 文件)?，在关于如何为 .Net Framework 实现整个事情的帖子中找到我的答案.*如果您已经在使用 .Net Core，答案将与我的相似，但您不必使用自定义 WinHTTPHandler.只需普通的 HTTPClient 即可.

1. For APNs, there are 2 ways of doing things. One is using .P12 conventional way. Another way is to use Apple Auth Keys using .P8. I prefer to use .P8 because .P12 cert expiry every year and need to update annually. The problem with using .P8 is that, it's using HTTP/2 which is not supported in .Net Framework but thankfully, I managed to overcome that. Please refer to How to implement apple token based push notifications (using p8 file) in C#?, find my Answer on that post on how to implement the whole thing for .Net Framework. *IF you're already using .Net Core, the answer will be similar to mine, but you do not have to use the custom WinHTTPHandler. Just the normal HTTPClient will do.

第 2 部分 Xamarin.Forms - 接下来，您必须支持 Xamarin.Forms 项目中的通知.

PART 2 Xamarin.Forms - Next, you'll have to support the notification in your Xamarin.Forms project.

1. 对于这部分，一点也不难.您所要做的就是参考 https://github.com/CrossGeeks/PushNotificationPlugin，下载Nuget 并按照链接中的说明为您的 Xamarin 项目(表单、Android、iOS)进行设置.

1. For this part, it's not very difficult at all. All you have to do is refer to https://github.com/CrossGeeks/PushNotificationPlugin, download the Nuget and follow the instructions in the link to setup for your Xamarin projects (Forms, Android, iOS).

我唯一想强调的是如何&从哪里获取您的设备令牌.最初，我试图通过下面的代码 (OnTokenRefresh) 获取设备令牌.但是您很快就会注意到这段代码并不总是被调用，我怀疑它只会在令牌刷新后才会被调用，而不是每次调试时都会被调用.为了每次都获得您的设备令牌，只需在您的项目中的任何位置调用 CrossPushNotification.Current.Token 即可.将该设备令牌注册到您的服务器后端.并使用设备令牌使用我在上面第 1 部分中的代码发送通知.

The only thing that I wish to highlight is how & where to get your device token. Initially I was trying to get the device token at the code below (OnTokenRefresh). But you'll soon to notice that this code doesn't always get called, I suspect it will only get called once the token is refreshed, and not every time when you debug. In order to obtain your Device Token every time, just call CrossPushNotification.Current.Token anywhere in your project. Register that device token to your server backend. And use the device token to send the notification using my code at PART 1 above.

CrossPushNotification.Current.OnTokenRefresh += (s,p) =>
{
    System.Diagnostics.Debug.WriteLine($"TOKEN : {p.Token}");
};

就是这样！这很容易，但在将它们拼凑在一起之前，我花了数周的时间来尝试和出错.希望它能够为他人节省宝贵的时间.

That's it! It's pretty easy, but I spent weeks to try and error before piecing them together. Hope that it's able to save precious time from others.

这篇关于如何使用 Firebase 在 Xamarin 中实现推送通知和使用 C# 后端的 Apple 推送通知的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！