Create a message thread

When a user replies to a message in a channel, it creates a message thread, which refers to a collection of messages consisting of a parent message and its replies. Message threading lets users ask questions, give feedback, or add context to a specific message without disrupting the flow of conversation. It can have the following elements.

• A message can have a thread of replies.

• A message that has a thread of replies is a parent message.

• A parent message and its threaded replies are collectively called a message thread.

• Every message within a thread, whether it's parent or reply, is a threaded message.

• A message that doesn't have any replies is an unthreaded message.

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Message threading has the following limitations.

• Only 1-depth threads are supported, meaning you can only add reply messages to non-reply messages. You can't add a reply to a reply message.
• Message threading is limited to text and file messages. You can't send admin messages as replies or add replies to admin messages.

You can reply to a message in a channel through the sendUserMessage(params:completionHandler:) or sendFileMessage(params:completionHandler:) method. To do so, you should create a UserMessageCreateParams or a FileMessageCreateParams object and then specify the parentMessageId property of the object. Sending reply messages works the same way as sending regular messages to a channel except that replies have an additional parentMessageId property.

When replying to a message through the sendUserMessage(params:completionHandler:) method, you should specify and pass a UserMessageCreateParamsobject to the method as a parameter. The UserMessageCreateParams class is derived from the BaseMessageCreateParams class and can access all the methods and properties of BaseMessageCreateParams.

// Create a UserMessageCreateParams object.
let params = UserMessageCreateParams(message: MESSAGE_TEXT)
params.parentMessageId = PARENT_MESSAGE_ID
params.translationTargetLanguages = TARGET_LANGUAGE
params.mentionedMessageTemplate = MESSAGE_TEMPLATE

channel.sendUserMessage(params: params) { message, error in
    guard error == nil else {
        // Handle error.
        return
    }

    // A reply to a specific message is successfully sent as a text message.
}

To see the comprehensive list of all available methods and properties, see UserMessageCreateParams.

When replying with a file message through the sendFileMessage(params:completionHandler:) method, you should specify and pass a FileMessageCreateParams object to the method as a parameter. The FileMessageCreateParams class is derived from the BaseMessageCreateParams class and can access all the methods and properties of BaseMessageCreateParams.

// Create a FileMessageCreateParams object.
let params = FileMessageCreateParams(file: FILE)
params.parentMessageId = PARENT_MESSAGE_ID // This specifies the unique ID of a parent message which has a thread of replies. If the message sent through the `sendFileMessage(params:completionHandler:)` method is a parent message, the value of this property is 0.
params.fileName = FILE_NAME
params.mimeType = MIME_TYPE
params.fileSize = FILE_SIZE

channel.sendFileMessage(params: params) { message, error in
    guard error == nil else {
        // Handle error.
        return
    }

    // A reply to a specific message is successfully sent as a file message.
}

To see the comprehensive list of all available methods and properties, see FileMessageCreateParams.

When replying with more than two images or videos through the sendMultipleFilesMessage() method, you should specify and pass a MultipleFilesMessageCreateParams object to the method as a parameter. Just like FileMessageCreateParams, the MultipleFilesMessageCreateParams class is derived from the BaseMessageCreateParams class and can access all the methods and properties of BaseMessageCreateParams. To learn more about how to send a multiple file message, see the Send a message page.

FILEINFO_1.fileName = FILE_NAME_1
FILEINFO_1.mimeType = MIME_TYPE_1
FILEINFO_1.fileSize = FILE_SIZE_1

// Create a MultipleFilesMessageCreateParams object.
let params = MultipleFilesMessageCreateParams(uploadableFileInfoList: [FILEINFO_1, FILEINFO_2])
params.parentMessageId = PARENT_MESSAGE_ID // This specifies the unique ID of a parent message which has a thread of replies. If the message sent through the `sendMultipleFilesMessage(params:fileUploadHandler:completionHandler:)` method is a parent message, the value of this property is 0.  
channel.sendMultipleFilesMessage(params: params) { message, error in
    guard error == nil else {
        // Handle error.
        return
    }
    // A reply to a specific message is successfully sent as a multiple files message.
}

When a reply is created in a channel, the channel(_:didReceive:) and channel(_:didUpdateThreadInfo:) methods of the channel event delegate in client apps are called. When a reply is deleted from a thread, the channel(_:didUpdateThreadInfo:) event delegate method is invoked. In both cases, channel(_:didUpdateThreadInfo:) takes a ThreadInfoUpdateEvent object as an argument that has the latest information about the thread. Apply the object to the parent message object through the message.apply() method.

func channel(_ channel: BaseChannel, didUpdateThreadInfo threadInfoUpdateEvent: ThreadInfoUpdateEvent) {
    // Look for a message that has threadInfoUpdateEvent.targetMessageId.
    // Apply the event to the message.
    message.apply(threadInfoUpdateEvent)
}