Styled markdown with AttributedString (#3590)

* Add AttributedString extension for parsing markdown and enabling styling in the MarkdownFormatter

* Add tests for AttributedString markdown styling

* Use paragraph style for setting correct text alignment in lists

* Remove MarkdownStyles.linkFont because we use UITextView for rendering and UITextView overrides it

* Document linkFont removal and attributed string parsing

* Basic support for RTL and remove background color from code blocks

* Use unicode bullet for lists in markdown

* Be more careful with insertion index and skip parsing if string is empty

* Use Fonts for default fonts in markdown

* Remove SwiftyMarkdown

* Turn off markdown styles in the demo app

* Do not use markdown regex

Author: laevandus

.swiftlint.yml

@@ -4,7 +4,6 @@ excluded:
   - Dependencies
   - Sources/StreamChatUI/Generated
   - Sources/StreamChatUI/StreamSwiftyGif
-  - Sources/StreamChatUI/StreamSwiftyMarkdown
   - Sources/StreamChatUI/StreamNuke
   - Sources/StreamChat/StreamStarscream
   - Sources/StreamChatUI/StreamDifferenceKit
@@ -80,7 +79,8 @@ file_name_no_space:
   severity: error
 
 identifier_name:
-  excluded: [r, g, b, a, x, y, z, dx, dy, dz, i, j, k, id, op, or, me, at, to, in]
+  excluded:
+    [r, g, b, a, x, y, z, dx, dy, dz, i, j, k, id, op, or, me, at, to, in]
   allowed_symbols: ["_"]
   validates_start_with_lowercase: "warning"
 

CHANGELOG.md

@@ -3,7 +3,20 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 # Upcoming
 
+## StreamChat
+### ✅ Added
+- Add `MarkdownParser` for parsing and styling markdown strings [#3590](https://github.com/GetStream/stream-chat-swift/pull/3590)
+- Add `Fonts.title2` for supporting markdown headers [#3590](https://github.com/GetStream/stream-chat-swift/pull/3590)
+
+### StreamChatUI
 ### 🔄 Changed
+- Feature rich markdown rendering with `AttributedString` [#3590](https://github.com/GetStream/stream-chat-swift/pull/3590)
+  - Note: Markdown is rendered only on iOS 15 and above. On iOS 14 and below markdown is rendered as plain text
+  - Rename `MarkdownFormatter.format(_:)` to `MarkdownFormatter.format(_:attributes:)` for allowing to pass in current text attributes
+### 💥 Removed
+- Remove `MarkdownStyles.linkFont` because link attributes are ignored by `UITextView`. Update `ChatMessageContentView.textView.linkTextAttributes` instead [#3590](https://github.com/GetStream/stream-chat-swift/pull/3590)
+- Remove `DefaultMarkdownFormatter.markdownRegexPattern` because regular expression based validation was removed [#3590](https://github.com/GetStream/stream-chat-swift/pull/3590)
+- Remove `MarkdownFormatter.containsMarkdown(_:)`, optionally validate input strings in `MarkdownFormatter.format(_:attributes:)` instead [#3590](https://github.com/GetStream/stream-chat-swift/pull/3590)
 
 # [4.73.0](https://github.com/GetStream/stream-chat-swift/releases/tag/4.73.0)
 _February 27, 2025_

DemoApp/StreamChat/StreamChatWrapper+DemoApp.swift

@@ -67,17 +67,19 @@ extension StreamChatWrapper {
         Components.default.reactionsSorting = ReactionSorting.byFirstReactionAt
         Components.default.channelListErrorView = DemoChatChannelListErrorView.self
 
-        // Customize MarkdownFormatter
-        let defaultFormatter = DefaultMarkdownFormatter()
-        defaultFormatter.styles.bodyFont.color = .systemOrange
-        defaultFormatter.styles.codeFont.color = .systemPurple
-        defaultFormatter.styles.h1Font.color = .systemBlue
-        defaultFormatter.styles.h2Font.color = .systemRed
-        defaultFormatter.styles.h3Font.color = .systemYellow
-        defaultFormatter.styles.h4Font.color = .systemGreen
-        defaultFormatter.styles.h5Font.color = .systemBrown
-        defaultFormatter.styles.h6Font.color = .systemPink
-        Appearance.default.formatters.markdownFormatter = defaultFormatter
+        // Example of how to customize Markdown
+        /*
+         let defaultFormatter = DefaultMarkdownFormatter()
+         defaultFormatter.styles.bodyFont.color = .systemOrange
+         defaultFormatter.styles.codeFont.color = .systemPurple
+         defaultFormatter.styles.h1Font.color = .systemBlue
+         defaultFormatter.styles.h2Font.color = .systemRed
+         defaultFormatter.styles.h3Font.color = .systemYellow
+         defaultFormatter.styles.h4Font.color = .systemGreen
+         defaultFormatter.styles.h5Font.color = .systemBrown
+         defaultFormatter.styles.h6Font.color = .systemPink
+         Appearance.default.formatters.markdownFormatter = defaultFormatter
+         */
     }
 }
 

Makefile

@@ -46,8 +46,6 @@ update_dependencies:
 	make update_nuke version=10.3.3
 	echo "👉 Updating SwiftyGif"
 	make update_swiftygif version=5.4.2
-	echo "👉 Updating SwiftyMarkdown"
-	make update_swiftymarkdown version=master
 	echo "👉 Updating DifferenceKit"
 	make update_differencekit version=1.3.0
 
@@ -59,10 +57,6 @@ update_swiftygif: check_version_parameter
 	./Scripts/updateDependency.sh $(version) Dependencies/SwiftyGif Sources/StreamChatUI/StreamSwiftyGif SwiftyGif
 	./Scripts/removePublicDeclarations.sh Sources/StreamChatUI/StreamSwiftyGif
 
-update_swiftymarkdown: check_version_parameter
-	./Scripts/updateDependency.sh $(version) Dependencies/SwiftyMarkdown Sources/StreamChatUI/StreamSwiftyMarkdown Sources
-	./Scripts/removePublicDeclarations.sh Sources/StreamChatUI/StreamSwiftyMarkdown
-
 update_differencekit: check_version_parameter
 	./Scripts/updateDependency.sh $(version) Dependencies/DifferenceKit Sources/StreamChatUI/StreamDifferenceKit Sources
 	./Scripts/removePublicDeclarations.sh Sources/StreamChatUI/StreamDifferenceKit

Scripts/run-linter.sh

@@ -4,7 +4,7 @@ set -euo pipefail
 echo -e "👉 Running SwiftFormat Linting"
 
 echo -e "👉 Linting Sources..."
-mint run swiftformat --lint --config .swiftformat Sources --exclude **/Generated,Sources/StreamChatUI/StreamNuke,Sources/StreamChatUI/StreamSwiftyGif,Sources/StreamChatUI/StreamSwiftyMarkdown,Sources/StreamChatUI/StreamDifferenceKit
+mint run swiftformat --lint --config .swiftformat Sources --exclude **/Generated,Sources/StreamChatUI/StreamNuke,Sources/StreamChatUI/StreamSwiftyGif,Sources/StreamChatUI/StreamDifferenceKit
 
 echo -e "👉 Linting Tests..."
 mint run swiftformat --lint --config .swiftformat Tests

Scripts/updateDependency.sh

@@ -25,8 +25,6 @@ if [[ $dependency_directory == *"Nuke"* ]]; then
 	dependency_url="[email protected]:kean/Nuke.git"
 elif [[ $dependency_directory == *"SwiftyGif"* ]]; then
 	dependency_url="[email protected]:kirualex/SwiftyGif.git"
-elif [[ $dependency_directory == *"SwiftyMarkdown"* ]]; then
-    dependency_url="[email protected]:GetStream/SwiftyMarkdown.git"
 elif [[ $dependency_directory == *"DifferenceKit"* ]]; then
 	dependency_url="[email protected]:ra1028/DifferenceKit.git"
 else
@@ -70,10 +68,3 @@ if [[ $dependency_directory == *"DifferenceKit"* ]]; then
     # We currently use customized UIKit extensions in Utils/DifferenceKit+Stream.swift
     rm $output_directory/Extensions/UIKitExtension.swift
 fi
-
-if [[ $dependency_directory == *"SwiftyMarkdown"* ]]; then
-    # We currently use customized version of SwiftyMarkdown
-	git restore $output_directory/SwiftyMarkdown/PerformanceLog.swift || true
-    git restore $output_directory/SwiftyMarkdown/SwiftyLineProcessor.swift || true
-    git restore $output_directory/SwiftyMarkdown/SwiftyTokeniser.swift || true
-fi