Create message drafts

A MessageDraft object is an abstraction for composing a message that has not yet been published. You can use it to:

• Edit text before it is published
• Add channel references, user mentions, links
• Attach files

You can display user mentions, channel references, and links (collectively called "message elements") to the user on the front end of your application by adding a message draft change listener.

Basics

Message drafts consist of MessageElement objects, which can be either instances of plainText or link.

plainText are simple strings, while link elements are used for user mentions, channel references, and URLs. They contain a text and a reference to the linked element regardless if it's a user, a channel, or a URL.

Each link implements a MentionTarget interface, which defines the type of mention. Available targets include:

• MentionTarget.user(userId: String)
• MentionTarget.channel(channelId: String)
• MentionTarget.url(url: String)

Store draft messages locally

Swift Chat SDK does not provide a method for storing the drafted message on the client, so whenever a user drafts a message in a chat app, changes a channel, and goes back to that channel, the drafted message gets lost.

To save drafted messages before they are published on channels, implement your own local storage mechanism suitable for the platform you use.

Class diagram

Example

Consider the message Hey, I sent Alex this link on the #offtopic channel. where:

• Alex is a reference to the user with the ID of alex_d
• link is a URL of the www.pubnub.com website
• #offtopic is a reference to the channel with the ID of group.offtopic

The list of MessageElement objects returned by the MessageDraftChangeListener is as follows:

Part of Message	Element Type	Code Used to Create
Hey, I sent	plainText	messageDraft.update(text = "Hey, I sent Alex this link on the #offtopic channel.")
Alex	link	messageDraft.addMention(offset = 12, length = 4, target = MentionTarget.User(userId = "alex_d"))
this	plainText	messageDraft.update(text = "Hey, I sent Alex this link on the #offtopic channel.")
link	link	messageDraft.addMention(offset = 22, length = 4, target = MentionTarget.Url(url = "www.pubnub.com"))
on the	plainText	messageDraft.update(text = "Hey, I sent Alex this link on the #offtopic channel.")
#offtopic	link	messageDraft.addMention(offset = 34, length = 9, target = MentionTarget.Channel(channelId = "group.offtopic"))
channel.	plainText	messageDraft.update(text = "Hey, I sent Alex this link on the #offtopic channel.")

Internal mention format

By internally leveraging a Markdown-like syntax, the message draft format integrates links directly into the message text using the pattern [link text](link target) understood by the Swift Chat SDK.

Mention Type	Example
user	[John Doe](pn-user://john_doe)
channel	[General Chat](pn-channel://group.chat.123)
url	[PubNub](https://www.pubnub.com)

Custom schemas like pn-user:// and pn-channel:// are used to identify user and channel mentions, while traditional URLs are supported as-is.

Adding message elements

You don't use this Markdown-like syntax when adding message elements. It's only a representation of your message elements under the hood.

For more information, refer to Add message element.

Create a draft message

createMessageDraft() creates a message draft (MessageDraft object) that can consist of:

• Plain text
• Files
• Mentioned users
• Referenced channels
• Links

Method signature

This method has the following signature:

1channel.createMessageDraft(
2  userSuggestionSource: UserSuggestionSource = .channel,
3  isTypingIndicatorTriggered: Bool = true,
4  userLimit: Int = 10,
5  channelLimit: Int = 10
6) -> MessageDraftImpl

Input

* required

Parameter	Description
userSuggestionSource Type: UserSuggestionSource = .channel or UserSuggestionSource = .global Default: UserSuggestionSource = .channel	This parameter refers to the Mentions feature. Data source from which you want to retrieve users. You can choose either the list of channel members (.channel) or users on the app's Admin Portal keyset (.global).
isTypingIndicatorTriggered Type: Bool Default: true	This parameter refers to the Typing Indicator feature. Defines if the typing indicator should be enabled when writing the message.
userLimit Type: Int Default: 10	This parameter refers to the Mentions feature. Maximum number of usernames (name field from the User object) you can mention in one message. The default value is 10, the min is 1, and max is 100.
channelLimit Type: Int Default: 10	This parameter refers to the References feature. Maximum number of channel names (name field from the Channel object) you can reference in one message. The default value is 10, the min is 1, and max is 100.

Output

Parameter	Description
MessageDraftType	Instance of MessageDraftType, which represents a draft version of a message with the content, all links, referenced channels, mentioned users and their names.

Sample code

Create a draft message containing just plain text.

1let messageDraft = channel.createMessageDraft(isTypingIndicatorTriggered: channel.type != .public)

Add message draft change listener

Add a MessageDraftChangeListener to listen for changes to the contents of a message draft, as well as to retrieve the current message elements suggestions for user mentions, channel reference, and links. For example, when the message draft contains ... @name ... or ... #chann ....

Method signature

This method has the following signature:

1messageDraft.addChangeListener(_ listener: MessageDraftChangeListener)
2

3public protocol MessageDraftChangeListener: AnyObject {
4  /// Called when there is a change in the message elements or suggested mentions.
5  func onChange(messageElements: [MessageElement], suggestedMentions: any FutureObject<[SuggestedMention]>)
6}

Input

Parameter	Description
_ listener Type: MessageDraftChangeListener	The listener that receives the most current message elements and suggestions list.

MessageDraftChangeListener

Parameter

Description

onChange(messageElements: [MessageElement], suggestedMentions: any FutureObject<[SuggestedMention]>) Type: function

messageElements: [MessageElement] - this parameter is a list of MessageElement objects, representing the current state of the message draft. This could contain a mix of plain text and links, channel references, or user mentions. suggestedMentions: any FutureObject<[SuggestedMention]> - this parameter is a FutureObject containing a list of SuggestedMention objects. These are potential suggestions for message elements based on the current text in the draft.

SuggestedMention

A SuggestedMention represents a potential mention suggestion received from MessageDraftChangeListener.

Parameter	Description
offset Type: Int	The position from the start of the message draft where the message elements starts. It's counted from the beginning of the message (including spaces), with 0 as the first character.
replaceFrom Type: String	The original text at the given offset in the message draft text.
replaceWith Type: String	The suggested replacement for the replaceFrom text.
target Type: MentionTarget	The message element type. Available types include: MentionTarget.user(userId: String) MentionTarget.channel(channelId: String) MentionTarget.url(url: String)

Output

This method doesn't return any data.

Sample code

Add the listener to your message draft.

1// Create a message draft.
2// Assuming you have a reference of type "ChannelImpl" named "channel"
3let messageDraft = channel.createMessageDraft(isTypingIndicatorTriggered: channel.type != .public)
4// Create the listener
5let listener = ClosureMessageDraftChangeListener() { elements, suggestedMentions in
6  // updateUI(with:) is your own function for updating UI
7  updateUI(with: elements)
8  
9  suggestedMentions.async { result in
10    switch result {
11    case .success(let mentions):
12      // updateSuggestions(with:) is your own function for displaying suggestions
13      updateSuggestions(with: mentions)
14    case .failure(let error):
15      print("Error retrieving suggestions: \(error)")
16    }
17  }
18}
19

20// Add the listener
21messageDraft.addChangeListener(listener)

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Remove message draft change listener

Remove a previously added MessageDraftChangeListener.

Method signature

This method has the following signature:

1messageDraft.removeChangeListener(_ listener: MessageDraftChangeListener)

Input

Parameter	Description
_ listener Type: MessageDraftChangeListener	The listener to remove.

Output

This method doesn't return any data.

Sample code

Remove a listener from your message draft.

1// Create a message draft.
2// Assuming you have a reference of type "ChannelImpl" named "channel"
3let messageDraft = channel.createMessageDraft(isTypingIndicatorTriggered: channel.type != .public)
4// Define the listener
5let listener = ClosureMessageDraftChangeListener() { elements, suggestedMentions in
6  // updateUI(with:) is your own function for updating UI
7  updateUI(with: elements)
8  
9  suggestedMentions.async { result in
10    switch result {
11    case .success(let mentions):
12      // updateSuggestions(with:) is your own function for displaying suggestions
13      updateSuggestions(with: mentions)
14    case .failure(let error):
15      print("Error retrieving suggestions: \(error)")
16    }
17  }
18}
19

20// Add the listener to the message draft
21messageDraft.addChangeListener(listener)
22// Remove the listener from the message draft
23messageDraft.removeChangeListener(listener)

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Add message element

addMention() adds a user mention, channel reference or a link specified by a mention target at a given offset.

Method signature

This method has the following signature:

1messageDraft.addMention(
2  offset: Int, 
3  length: Int, 
4  target: MentionTarget
5)

Input

* required

Parameter	Description
offset * Type: Int Default: n/a	Position of a character in a message where the message element you want to insert starts. It's counted from the beginning of the message (including spaces), with 0 as the first character.
length * Type: Int Default: n/a	Number of characters the message element should occupy in the draft message's text.
target * Type: MentionTarget Default: n/a	Message element type. Available types include: MentionTarget.user(userId: String) MentionTarget.channel(channelId: String) MentionTarget.url(url: String)

Output

This method returns no output data.

Sample code

Create the Hello Alex! I have sent you this link on the #offtopic channel. message where Alex is a user mention, link is a URL, and #offtopic is a channel reference.

1// Create an empty message draft.
2// Assuming you have a reference of type "ChannelImpl" named "channel"
3let messageDraft = channel.createMessageDraft(isTypingIndicatorTriggered: channel.type != .public)
4// Add initial text
5messageDraft.update(text: "Hello Alex!")
6// Add a user mention to the string "Alex"
7messageDraft.addMention(offset: 6, length: 4, target: .user(userId: "alex_d"))
8// Change the text
9messageDraft.update(text: "Hello Alex! I have sent you this link on the #offtopic channel.")
10// Add a URL mention to the string "link"
11messageDraft.addMention(offset: 33, length: 4, target: .url(url: "www.pubnub.com"))
12// Add a channel mention to the string "#offtopic"
13messageDraft.addMention(offset: 45, length: 9, target: .channel(channelId: "group.offtopic"))

Remove message element

removeMention() removes a user mention, channel reference, or a link at a given offset.

Method signature

This method has the following signature:

1messageDraft.removeMention(offset: Int)

Input

* required

Parameter	Description
offset * Type: Int Default: n/a	Position of the first character of the message element you want to remove.

Offset value

If you don't provide the position of the first character of the message element to remove, it isn't removed.

Output

This method returns no output data.

Sample code

Remove the URL element from the word link in the Hello Alex! I have sent you this link on the #offtopic channel. message.

1// Assume the message reads: "Hello Alex! I have sent you this link on the #offtopic channel."
2// Remove the link mention
3messageDraft.removeMention(offset: 33)

Update message text

update() lets you replace the text of a draft message with new content.

Removing message elements

As a best effort, the optimal set of insertions and removals that converts the current text to the provided text is calculated to preserve any message elements.

If any message element text is found to be modified in the updated text, the message element is removed.

Method signature

This method has the following signature:

1messageDraft.update(text: String)

Input

* required

Parameter	Description
text * Type: string Default: n/a	Text of the message that you want to update.

Output

This method returns no output data.

Sample code

Change the message I sent Alex this picture. to I did not send Alex this picture. where Alex is a user mention.

1// The message reads: "I sent [Alex] this picture."
2// Where [Alex] is a user mention
3messageDraft.update(text: "I did not send Alex this picture.")
4// The message now reads: "I did not send [Alex] this picture."
5// The mention is preserved because its text wasn't changed

Mention text changes

If you decided to change the name Alex to some other name, the mention would be removed because your updated text's index coincided with an existing mention.

For more manual control over inserting and removing parts of a message, refer to Insert message text and Remove message text.

Insert suggested message element

Inserts a message element returned by the MessageDraftChangeListener into the MessageDraft.

Text must match

The SuggestedMention must be up to date with the message text, that is, SuggestedMention.replaceFrom must match the message draft at position SuggestedMention.replaceFrom, otherwise an exception is thrown.

Method signature

This method has the following signature:

1messageDraft.insertSuggestedMention(
2  mention: SuggestedMention, 
3  text: String
4)

Input

* required

Parameter	Description
mention * Type: SuggestedMention Default: n/a	A user, channel, or URL suggestion obtained from MessageDraftChangeListener.
text * Type: string Default: n/a	The text you want the message element to display.

Output

This method returns no output data.

Sample code

Register a listener and insert a suggested element.

1// Create a message draft.
2// Assuming you have a reference of type "ChannelImpl" named "channel"
3let messageDraft = channel.createMessageDraft(isTypingIndicatorTriggered: channel?.type != .public)
4// Create the listener
5let listener = ClosureMessageDraftChangeListener() { elements, suggestedMentions in
6  // updateUI() is your own function for updating the UI:
7  updateUI(elements) 
8  suggestedMentions.async { result in
9    switch result {
10    case .success(let mentions):
11      // updateSuggestions() is your own function for displaying suggestions
12      updateSuggestions(mentions) 
13    case .failure(let error):
14      print("Error retrieving suggestions: \(error)")
15    }
16  }
17}
18

19messageDraft.addChangeListener(listener)
20

21// Assuming that getSelectedSuggestion() is your own function that returns a suggestion selected by the user.
22// When the user selects a suggestion in the UI:
23if let suggestion = getSelectedSuggestion() {
24    messageDraft.insertSuggestedMention(mention: suggestion, text: suggestion.replaceWith)
25}

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Insert message text

insertText() lets you insert plain text in the draft message at a given offset from the beginning of the message.

Removing message elements

If the position of the text you want to insert corresponds to an existing message element, this element is removed.

Method signature

This method has the following signature:

1messageDraft.insertText(
2    offset: Int, 
3    text: String
4)

Input

* required

Parameter	Description
offset * Type: Int Default: n/a	Position of a character in a message where the text you want to insert starts. It's counted from the beginning of the message (including spaces), with 0 as the first character.
text * Type: string Default: n/a	Text that you want to insert.

Output

This method returns no output data.

Sample code

In the message Check this support article https://www.support-article.com/., add the word out between the words Check and this.

1// The message reads: "Check this support article https://www.support-article.com/."
2messageDraft.insertText(offset: 6, text: "out ")
3// The message now reads: "Check out this support article https://www.support-article.com/"

Remove message text

removeText() lets you remove plain text from the draft message at a given offset from the beginning of the message.

Removing message elements

If the position of the text you want to remove corresponds to an existing message element, this element is removed.

Method signature

This method has the following signature:

1messageDraft.removeText(
2    offset: Int, 
3    length: Int
4)

Input

* required

Parameter	Description
offset * Type: Int Default: n/a	Position of a character in a message where the text you want to insert starts. It's counted from the beginning of the message (including spaces), with 0 as the first character.
length * Type: Int Default: n/a	How many characters to remove, starting at the given offset.

Output

This method returns no output data.

Sample code

In the message Check out this support article https://www.support-article.com/., remove the word out.

1// The message reads: "Check out this support article https://www.support-article.com/."
2messageDraft.removeText(offset: 5, length: 4)
3// The message now reads: "Check this support article https://www.support-article.com/."

Send a draft message

send() publishes the draft text message with all mentioned users, links, and referenced channels.

Whenever you mention any users, send() also emits events of type mention.

Method signature

This method has the following signature:

1messageDraft.send(
2  meta: [String: JSONCodable]? = null,
3  shouldStore: Bool = true,
4  usePost: Bool = false,
5  ttl: Int? = null
6) async throws -> Timetoken

Input

* required

Parameter	Description
meta Type: [String: JSONCodable] Default: n/a	Additional details of the request.
shouldStore Type: Bool Default: true	If true, the messages are stored in Message Persistence (PubNub storage). If shouldStore is not specified, the Message Persistence configuration specified on the Admin Portal keyset is used.
usePost Type: Bool Default: false	When true, the SDK uses HTTP POST to publish the messages. The message is sent in the BODY of the request instead of the query string when HTTP GET is used. The messages are also compressed to reduce their size.
ttl Type: Int? Default: n/a	Defines if / how long (in hours) the message should be stored in Message Persistence. If shouldStore = true, and ttl = 0, the message is stored with no expiry time. If shouldStore = true and ttl = X, the message is stored with an expiry time of X hours unless you have message retention set to Unlimited on your keyset configuration in the Admin Portal. If shouldStore = false, the ttl parameter is ignored. If ttl is not specified, then the expiration of the message defaults back to the expiry value for the keyset.

Suppose a user adds elements to the message draft, such as links, quotes, other user mentions, or channel references. In that case, these are not explicitly passed in the send() method but get added to the MessageDraft object through the addMention() and addQuote() methods.

Output

Parameter	Description
Timetoken	Timetoken of the message.

Sample code

Send a draft message containing just plain text.

1Task {
2  // Create a message draft.
3  // Assuming you have a reference of type "ChannelImpl" named "channel"
4  let messageDraft = channel.createMessageDraft(isTypingIndicatorTriggered: channel.type != .public)
5  // Add text
6  messageDraft.update(text: "Hello!")
7  // Send the message
8  try await messageDraft.send()
9}