Allow customisation of message previews in lists

Author: laevandus

Sources/StreamChatSwiftUI/Utils.swift

@@ -8,8 +8,6 @@ import StreamChat
 /// Class providing implementations of several utilities used in the SDK.
 /// The default implementations can be replaced in the init method, or directly via the variables.
 public class Utils {
-    // TODO: Make it public in future versions.
-    internal var messagePreviewFormatter = MessagePreviewFormatter()
     var markdownFormatter = MarkdownFormatter()
 
     public var dateFormatter: DateFormatter
@@ -29,6 +27,7 @@ public class Utils {
     public var channelAvatarsMerger: ChannelAvatarsMerging
     public var messageTypeResolver: MessageTypeResolving
     public var messageActionsResolver: MessageActionsResolving
+    public var messagePreviewFormatter: MessagePreviewFormatting
     public var commandsConfig: CommandsConfig
     public var channelListConfig: ChannelListConfig
     public var messageListConfig: MessageListConfig
@@ -87,6 +86,7 @@ public class Utils {
         channelAvatarsMerger: ChannelAvatarsMerging = ChannelAvatarsMerger(),
         messageTypeResolver: MessageTypeResolving = MessageTypeResolver(),
         messageActionResolver: MessageActionsResolving = MessageActionsResolver(),
+        messagePreviewFormatter: MessagePreviewFormatting = MessagePreviewFormatter(),
         commandsConfig: CommandsConfig = DefaultCommandsConfig(),
         channelListConfig: ChannelListConfig = ChannelListConfig(),
         messageListConfig: MessageListConfig = MessageListConfig(),
@@ -115,6 +115,7 @@ public class Utils {
         self.channelAvatarsMerger = channelAvatarsMerger
         self.messageTypeResolver = messageTypeResolver
         messageActionsResolver = messageActionResolver
+        self.messagePreviewFormatter = messagePreviewFormatter
         self.commandsConfig = commandsConfig
         self.channelListConfig = channelListConfig
         self.messageListConfig = messageListConfig

Sources/StreamChatSwiftUI/Utils/MessagePreviewFormatter.swift

@@ -5,23 +5,33 @@
 import StreamChat
 import SwiftUI
 
+/// Provides message preview representation for lists.
+public protocol MessagePreviewFormatting {
+    /// Formats the message including the author's name.
+    func format(_ previewMessage: ChatMessage, in channel: ChatChannel) -> String
+    /// Formats only the content of the message without the author's name.
+    func formatContent(for previewMessage: ChatMessage, in channel: ChatChannel) -> String
+    /// Formats only the attachment content of the message in case it contains attachments.
+    func formatAttachmentContent(for previewMessage: ChatMessage, in channel: ChatChannel) -> String?
+}
+
 /// A formatter that converts a message to a text preview representation.
 /// By default it is used to show message previews in the Channel List and Thread List.
-struct MessagePreviewFormatter {
+open class MessagePreviewFormatter: MessagePreviewFormatting {
     @Injected(\.chatClient) var chatClient
 
-    init() {}
+    public init() {}
 
     /// Formats the message including the author's name.
-    func format(_ previewMessage: ChatMessage, in channel: ChatChannel) -> String {
+    open func format(_ previewMessage: ChatMessage, in channel: ChatChannel) -> String {
         if let poll = previewMessage.poll {
             return formatPoll(poll)
         }
         return "\(previewMessage.author.name ?? previewMessage.author.id): \(formatContent(for: previewMessage, in: channel))"
     }
 
     /// Formats only the content of the message without the author's name.
-    func formatContent(for previewMessage: ChatMessage, in channel: ChatChannel) -> String {
+    open func formatContent(for previewMessage: ChatMessage, in channel: ChatChannel) -> String {
         if let attachmentPreviewText = formatAttachmentContent(for: previewMessage, in: channel) {
             return attachmentPreviewText
         }
@@ -32,7 +42,7 @@ struct MessagePreviewFormatter {
     }
 
     /// Formats only the attachment content of the message in case it contains attachments.
-    func formatAttachmentContent(for previewMessage: ChatMessage, in channel: ChatChannel) -> String? {
+    open func formatAttachmentContent(for previewMessage: ChatMessage, in channel: ChatChannel) -> String? {
         if let poll = previewMessage.poll {
             return "📊 \(poll.name)"
         }