Unescape XML entities in notification body

Metatext.xcodeproj/project.pbxproj

@@ -50,6 +50,7 @@
 		D059373425AAEA7000754FDF /* CompositionPollView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D059373225AAEA7000754FDF /* CompositionPollView.swift */; };
 		D059373E25AB8D5200754FDF /* CompositionPollOptionView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D059373D25AB8D5200754FDF /* CompositionPollOptionView.swift */; };
 		D059373F25AB8D5200754FDF /* CompositionPollOptionView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D059373D25AB8D5200754FDF /* CompositionPollOptionView.swift */; };
+		D059376125ABE2E800754FDF /* XMLUnescaper.swift in Sources */ = {isa = PBXBuildFile; fileRef = D059376025ABE2E800754FDF /* XMLUnescaper.swift */; };
 		D0625E59250F092900502611 /* StatusListCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0625E58250F092900502611 /* StatusListCell.swift */; };
 		D0625E5D250F0B5C00502611 /* StatusContentConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = D0625E5C250F0B5C00502611 /* StatusContentConfiguration.swift */; };
 		D06BC5E625202AD90079541D /* ProfileViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D06BC5E525202AD90079541D /* ProfileViewController.swift */; };
@@ -202,6 +203,7 @@
 		D05936FE25AA94EA00754FDF /* MarkAttachmentsSensitiveView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MarkAttachmentsSensitiveView.swift; sourceTree = "<group>"; };
 		D059373225AAEA7000754FDF /* CompositionPollView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CompositionPollView.swift; sourceTree = "<group>"; };
 		D059373D25AB8D5200754FDF /* CompositionPollOptionView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CompositionPollOptionView.swift; sourceTree = "<group>"; };
+		D059376025ABE2E800754FDF /* XMLUnescaper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = XMLUnescaper.swift; sourceTree = "<group>"; };
 		D0625E58250F092900502611 /* StatusListCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusListCell.swift; sourceTree = "<group>"; };
 		D0625E5C250F0B5C00502611 /* StatusContentConfiguration.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusContentConfiguration.swift; sourceTree = "<group>"; };
 		D0666A2124C677B400F3F04B /* Tests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = Tests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -563,6 +565,7 @@
 				D0E5361D24E3EB4D00FB1CE1 /* Info.plist */,
 				D0E5362824E4A06B00FB1CE1 /* Notification Service Extension.entitlements */,
 				D0E5361B24E3EB4D00FB1CE1 /* NotificationService.swift */,
+				D059376025ABE2E800754FDF /* XMLUnescaper.swift */,
 			);
 			path = "Notification Service Extension";
 			sourceTree = "<group>";
@@ -911,6 +914,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				D0E5361C24E3EB4D00FB1CE1 /* NotificationService.swift in Sources */,
+				D059376125ABE2E800754FDF /* XMLUnescaper.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Notification Service Extension/NotificationService.swift

@@ -32,7 +32,7 @@ final class NotificationService: UNNotificationServiceExtension {
         }
 
         bestAttemptContent.title = pushNotification.title
-        bestAttemptContent.body = pushNotification.body
+        bestAttemptContent.body = XMLUnescaper(string: pushNotification.body).unescape()
 
         let fileName = pushNotification.icon.lastPathComponent
         let fileURL = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true).appendingPathComponent(fileName)

Notification Service Extension/XMLUnescaper.swift

@@ -0,0 +1,37 @@
+// Copyright © 2021 Metabolist. All rights reserved.
+
+import Foundation
+
+final class XMLUnescaper: NSObject {
+    private let rawString: String
+    private let parser: XMLParser
+    private var unescaped = ""
+    private static let containerTag = "com.metabolist.metatext.container-tag"
+    private static let openingContainerTag = "<\(containerTag)>"
+    private static let closingContainerTag = "</\(containerTag)>"
+
+    init(string: String) {
+        rawString = Self.openingContainerTag
+            .appending(string)
+            .appending(Self.closingContainerTag)
+        parser = XMLParser(data: Data(rawString.utf8))
+
+        super.init()
+
+        parser.delegate = self
+    }
+}
+
+extension XMLUnescaper {
+    func unescape() -> String {
+        parser.parse()
+
+        return unescaped
+    }
+}
+
+extension XMLUnescaper: XMLParserDelegate {
+    func parser(_ parser: XMLParser, foundCharacters string: String) {
+        unescaped.append(string)
+    }
+}