本頁面由 Cloud Translation API 翻譯而成。

在 Apple 平台上傳送訊息至主題

視發布/訂閱模型而定，FCM 主題訊息功能可讓您將訊息傳送至已選擇加入特定主題的多部裝置。您可以視需要撰寫主題訊息，而 FCM 會妥善處理訊息轉送作業，並將訊息安全傳送至正確的裝置。

舉例來說，當地潮汐預測應用程式的使用者可以選擇訂閱「潮流警報」主題，接收特定地區最佳鹽水釣魚條件的通知。運動應用程式的使用者可以訂閱喜愛球隊的即時比數自動更新功能。

使用主題時，請注意下列事項：

主題訊息最適合用於天氣或其他公開資訊等內容。
主題訊息是針對總處理量而非延遲進行最佳化。如要以快速又安全的方式將訊息傳送至單一裝置或少數裝置，建議您將訊息傳送至註冊權杖，而非主題。
如果您需要向每位使用者的多台裝置傳送訊息，請考慮針對這些用途使用裝置群組訊息傳送。
每個主題的訊息功能支援無限次訂閱。不過，FCM 會在下列領域實施限制：
- 一個應用程式執行個體最多只能訂閱 2,000 個主題。
- 如果您使用批次匯入功能來訂閱應用程式執行個體，每個要求最多只能包含 1,000 個應用程式執行個體。
- 每個專案的新訂閱頻率都有限制。如果您在短時間內傳送太多訂閱要求，FCM 伺服器會傳回 429 RESOURCE_EXHAUSTED (「配額超出」) 回應。以指數輪詢方式重試。

讓用戶端應用程式訂閱主題

用戶端應用程式可以訂閱任何現有主題，也可以建立新主題。當用戶端應用程式訂閱新主題名稱 (在您的 Firebase 專案中不存在) 時，系統會在 FCM 中建立該名稱的新主題，之後任何用戶端都可以訂閱該主題。

如要訂閱主題，請從應用程式的主要執行緒呼叫訂閱方法 (FCM 不安全)。如果訂閱要求一開始失敗，FCM 會自動重試。如果無法完成訂閱，訂閱項目會擲回錯誤，您可以在完成處理常式中擷取這類錯誤，如下所示：

Swift

Messaging.messaging().subscribe(toTopic: "weather") { error in
  print("Subscribed to weather topic")
}ViewController.swift

Objective-C

[[FIRMessaging messaging] subscribeToTopic:@"weather"
                                completion:^(NSError * _Nullable error) {
  NSLog(@"Subscribed to weather topic");
}];ViewController.m

這個呼叫會向 FCM 後端發出非同步要求，並讓用戶端訂閱指定的主題。在呼叫 subscribeToTopic:topic 之前，請確認用戶端應用程式例項已透過回呼 didReceiveRegistrationToken 收到註冊權杖。

每次啟動應用程式時，FCM 都會確保已訂閱所有要求的主題。如要取消訂閱，請呼叫 unsubscribeFromTopic:topic，而 FCM 會在背景取消訂閱主題。

在伺服器上管理主題訂閱

Firebase Admin SDK 則可讓您在伺服器端執行基本的主題管理工作。只要提供註冊權杖，您就能使用伺服器邏輯大量訂閱及取消訂閱用戶端應用程式執行個體。

您可以訂閱用戶端應用程式執行個體到任何現有主題，或是建立新主題。當您使用 API 將用戶端應用程式訂閱至新主題 (您的 Firebase 專案中不存在的) 時，系統會在 FCM 中建立同名的新主題，之後任何用戶端都可以訂閱該主題。

您可以將註冊權杖清單傳遞至 Firebase Admin SDK 訂閱方法，藉此訂閱對應的裝置：

Node.js

// These registration tokens come from the client FCM SDKs.
const registrationTokens = [
  'YOUR_REGISTRATION_TOKEN_1',
  // ...
  'YOUR_REGISTRATION_TOKEN_n'
];

// Subscribe the devices corresponding to the registration tokens to the
// topic.
getMessaging().subscribeToTopic(registrationTokens, topic)
  .then((response) => {
    // See the MessagingTopicManagementResponse reference documentation
    // for the contents of response.
    console.log('Successfully subscribed to topic:', response);
  })
  .catch((error) => {
    console.log('Error subscribing to topic:', error);
  });

Java

// These registration tokens come from the client FCM SDKs.
List<String> registrationTokens = Arrays.asList(
    "YOUR_REGISTRATION_TOKEN_1",
    // ...
    "YOUR_REGISTRATION_TOKEN_n"
);

// Subscribe the devices corresponding to the registration tokens to the
// topic.
TopicManagementResponse response = FirebaseMessaging.getInstance().subscribeToTopic(
    registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
System.out.println(response.getSuccessCount() + " tokens were subscribed successfully");

Python

# These registration tokens come from the client FCM SDKs.
registration_tokens = [
    'YOUR_REGISTRATION_TOKEN_1',
    # ...
    'YOUR_REGISTRATION_TOKEN_n',
]

# Subscribe the devices corresponding to the registration tokens to the
# topic.
response = messaging.subscribe_to_topic(registration_tokens, topic)
# See the TopicManagementResponse reference documentation
# for the contents of response.
print(response.success_count, 'tokens were subscribed successfully')

Go

// These registration tokens come from the client FCM SDKs.
registrationTokens := []string{
	"YOUR_REGISTRATION_TOKEN_1",
	// ...
	"YOUR_REGISTRATION_TOKEN_n",
}

// Subscribe the devices corresponding to the registration tokens to the
// topic.
response, err := client.SubscribeToTopic(ctx, registrationTokens, topic)
if err != nil {
	log.Fatalln(err)
}
// See the TopicManagementResponse reference documentation
// for the contents of response.
fmt.Println(response.SuccessCount, "tokens were subscribed successfully")

C#

// These registration tokens come from the client FCM SDKs.
var registrationTokens = new List<string>()
{
    "YOUR_REGISTRATION_TOKEN_1",
    // ...
    "YOUR_REGISTRATION_TOKEN_n",
};

// Subscribe the devices corresponding to the registration tokens to the
// topic
var response = await FirebaseMessaging.DefaultInstance.SubscribeToTopicAsync(
    registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
Console.WriteLine($"{response.SuccessCount} tokens were subscribed successfully");FirebaseMessagingSnippets.cs

管理員 FCM API 還可讓您將裝置從主題取消訂閱，方法是將註冊權杖傳遞至適當的方法：

Node.js

// These registration tokens come from the client FCM SDKs.
const registrationTokens = [
  'YOUR_REGISTRATION_TOKEN_1',
  // ...
  'YOUR_REGISTRATION_TOKEN_n'
];

// Unsubscribe the devices corresponding to the registration tokens from
// the topic.
getMessaging().unsubscribeFromTopic(registrationTokens, topic)
  .then((response) => {
    // See the MessagingTopicManagementResponse reference documentation
    // for the contents of response.
    console.log('Successfully unsubscribed from topic:', response);
  })
  .catch((error) => {
    console.log('Error unsubscribing from topic:', error);
  });

Java

// These registration tokens come from the client FCM SDKs.
List<String> registrationTokens = Arrays.asList(
    "YOUR_REGISTRATION_TOKEN_1",
    // ...
    "YOUR_REGISTRATION_TOKEN_n"
);

// Unsubscribe the devices corresponding to the registration tokens from
// the topic.
TopicManagementResponse response = FirebaseMessaging.getInstance().unsubscribeFromTopic(
    registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
System.out.println(response.getSuccessCount() + " tokens were unsubscribed successfully");

Python

# These registration tokens come from the client FCM SDKs.
registration_tokens = [
    'YOUR_REGISTRATION_TOKEN_1',
    # ...
    'YOUR_REGISTRATION_TOKEN_n',
]

# Unubscribe the devices corresponding to the registration tokens from the
# topic.
response = messaging.unsubscribe_from_topic(registration_tokens, topic)
# See the TopicManagementResponse reference documentation
# for the contents of response.
print(response.success_count, 'tokens were unsubscribed successfully')

Go

// These registration tokens come from the client FCM SDKs.
registrationTokens := []string{
	"YOUR_REGISTRATION_TOKEN_1",
	// ...
	"YOUR_REGISTRATION_TOKEN_n",
}

// Unsubscribe the devices corresponding to the registration tokens from
// the topic.
response, err := client.UnsubscribeFromTopic(ctx, registrationTokens, topic)
if err != nil {
	log.Fatalln(err)
}
// See the TopicManagementResponse reference documentation
// for the contents of response.
fmt.Println(response.SuccessCount, "tokens were unsubscribed successfully")

C#

// These registration tokens come from the client FCM SDKs.
var registrationTokens = new List<string>()
{
    "YOUR_REGISTRATION_TOKEN_1",
    // ...
    "YOUR_REGISTRATION_TOKEN_n",
};

// Unsubscribe the devices corresponding to the registration tokens from the
// topic
var response = await FirebaseMessaging.DefaultInstance.UnsubscribeFromTopicAsync(
    registrationTokens, topic);
// See the TopicManagementResponse reference documentation
// for the contents of response.
Console.WriteLine($"{response.SuccessCount} tokens were unsubscribed successfully");FirebaseMessagingSnippets.cs

subscribeToTopic() 和 unsubscribeFromTopic() 方法會產生物件，其中包含 FCM 的回應。無論要求中指定的註冊符記號數量為何，傳回類型都會採用相同的格式。

如果發生錯誤 (驗證失敗、憑證無效或主題等)，這些方法就會發生錯誤。如需錯誤代碼的完整清單 (包括說明和解決步驟)，請參閱「Admin FCM API 錯誤」。

接收及處理主題訊息

FCM 傳送主題訊息的方式與其他下游訊息相同。

實作 application(_:didReceiveRemoteNotification:fetchCompletionHandler:)，如下所示：

Swift

func application(_ application: UIApplication,
                 didReceiveRemoteNotification userInfo: [AnyHashable: Any]) async
  -> UIBackgroundFetchResult {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // Messaging.messaging().appDidReceiveMessage(userInfo)

  // Print message ID.
  if let messageID = userInfo[gcmMessageIDKey] {
    print("Message ID: \(messageID)")
  }

  // Print full message.
  print(userInfo)

  return UIBackgroundFetchResult.newData
}
AppDelegate.swift

Objective-C

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
    fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[FIRMessaging messaging] appDidReceiveMessage:userInfo];

  // ...

  // Print full message.
  NSLog(@"%@", userInfo);

  completionHandler(UIBackgroundFetchResultNewData);
}AppDelegate.m

建立傳送要求

建立主題後，您可以透過訂閱用戶端應用程式執行個體，或透過伺服器 API，將訊息傳送至主題。如果這是您首次為 FCM 建立傳送要求，請參閱指南，瞭解伺服器環境和 FCM 的重要背景和設定資訊。

在後端的傳送邏輯中，指定所需的主題名稱，如下所示：

Node.js

// The topic name can be optionally prefixed with "/topics/".
const topic = 'highScores';

const message = {
  data: {
    score: '850',
    time: '2:45'
  },
  topic: topic
};

// Send a message to devices subscribed to the provided topic.
getMessaging().send(message)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });

Java

// The topic name can be optionally prefixed with "/topics/".
String topic = "highScores";

// See documentation on defining a message payload.
Message message = Message.builder()
    .putData("score", "850")
    .putData("time", "2:45")
    .setTopic(topic)
    .build();

// Send a message to the devices subscribed to the provided topic.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);FirebaseMessagingSnippets.java

Python

# The topic name can be optionally prefixed with "/topics/".
topic = 'highScores'

# See documentation on defining a message payload.
message = messaging.Message(
    data={
        'score': '850',
        'time': '2:45',
    },
    topic=topic,
)

# Send a message to the devices subscribed to the provided topic.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)cloud_messaging.py

Go

// The topic name can be optionally prefixed with "/topics/".
topic := "highScores"

// See documentation on defining a message payload.
message := &messaging.Message{
	Data: map[string]string{
		"score": "850",
		"time":  "2:45",
	},
	Topic: topic,
}

// Send a message to the devices subscribed to the provided topic.
response, err := client.Send(ctx, message)
if err != nil {
	log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)messaging.go

C#

// The topic name can be optionally prefixed with "/topics/".
var topic = "highScores";

// See documentation on defining a message payload.
var message = new Message()
{
    Data = new Dictionary<string, string>()
    {
        { "score", "850" },
        { "time", "2:45" },
    },
    Topic = topic,
};

// Send a message to the devices subscribed to the provided topic.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);

REST

POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
  "message":{
    "topic" : "foo-bar",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message"
      }
   }
}

cURL 指令：

curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "message": {
    "topic" : "foo-bar",
    "notification": {
      "body": "This is a Firebase Cloud Messaging Topic Message!",
      "title": "FCM Message"
    }
  }
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

如要將訊息傳送至主題組合，請指定條件，這是指定目標主題的布林運算式。舉例來說，下列條件會將訊息傳送至已訂閱 TopicA 和 TopicB 或 TopicC 的裝置：

"'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)"

FCM 會先評估括號中的任何條件，然後從左到右評估運算式。在上述運算式中，訂閱任何單一主題的使用者都不會收到訊息。同樣地，未訂閱 TopicA 的使用者也不會收到訊息。以下組合會收到這項通知：

TopicA 和 TopicB
TopicA 和 TopicC

條件運算式最多可加入五個主題。

如要傳送至條件：

Node.js

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
const condition = '\'stock-GOOG\' in topics || \'industry-tech\' in topics';

// See documentation on defining a message payload.
const message = {
  notification: {
    title: '$FooCorp up 1.43% on the day',
    body: '$FooCorp gained 11.80 points to close at 835.67, up 1.43% on the day.'
  },
  condition: condition
};

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
getMessaging().send(message)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });

Java

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
String condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
Message message = Message.builder()
    .setNotification(Notification.builder()
        .setTitle("$GOOG up 1.43% on the day")
        .setBody("$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.")
        .build())
    .setCondition(condition)
    .build();

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);FirebaseMessagingSnippets.java

Python

# Define a condition which will send to devices which are subscribed
# to either the Google stock or the tech industry topics.
condition = "'stock-GOOG' in topics || 'industry-tech' in topics"

# See documentation on defining a message payload.
message = messaging.Message(
    notification=messaging.Notification(
        title='$GOOG up 1.43% on the day',
        body='$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.',
    ),
    condition=condition,
)

# Send a message to devices subscribed to the combination of topics
# specified by the provided condition.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)cloud_messaging.py

Go

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
condition := "'stock-GOOG' in topics || 'industry-tech' in topics"

// See documentation on defining a message payload.
message := &messaging.Message{
	Data: map[string]string{
		"score": "850",
		"time":  "2:45",
	},
	Condition: condition,
}

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
response, err := client.Send(ctx, message)
if err != nil {
	log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)messaging.go

C#

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
var condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
var message = new Message()
{
    Notification = new Notification()
    {
        Title = "$GOOG up 1.43% on the day",
        Body = "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.",
    },
    Condition = condition,
};

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);

REST

POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
   "message":{
    "condition": "'dogs' in topics || 'cats' in topics",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message",
    }
  }
}

cURL 指令：

curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "notification": {
    "title": "FCM Message",
    "body": "This is a Firebase Cloud Messaging Topic Message!",
  },
  "condition": "'dogs' in topics || 'cats' in topics"
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

後續步驟

進一步瞭解傳送至多部裝置的其他方式：裝置群組訊息