Step container load data improvements

Stepic.xcodeproj/project.pbxproj

@@ -650,6 +650,13 @@
 		2CA3E8AF24C173C600FA3059 /* CourseInfoTabInfoAboutBlockView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA3E8AE24C173C600FA3059 /* CourseInfoTabInfoAboutBlockView.swift */; };
 		2CA47D4A248ABF0E00925335 /* LogoutDataClearService.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA47D49248ABF0E00925335 /* LogoutDataClearService.swift */; };
 		2CA51BB024AB9B4300A400AE /* NewProfileUserActivityViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA51BAF24AB9B4300A400AE /* NewProfileUserActivityViewModel.swift */; };
+		2CA9307B253C691F007B717A /* StepPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA9307A253C691F007B717A /* StepPlainObject.swift */; };
+		2CA93080253C6B03007B717A /* DiscussionThreadPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA9307F253C6B03007B717A /* DiscussionThreadPlainObject.swift */; };
+		2CA93088253C79C9007B717A /* AttemptPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA93087253C79C9007B717A /* AttemptPlainObject.swift */; };
+		2CA93091253C86D0007B717A /* VideoURLPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA93090253C86D0007B717A /* VideoURLPlainObject.swift */; };
+		2CA93099253C8760007B717A /* VideoPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA93098253C8760007B717A /* VideoPlainObject.swift */; };
+		2CA930A4253C884F007B717A /* BlockPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA930A3253C884F007B717A /* BlockPlainObject.swift */; };
+		2CA930B7253C8A65007B717A /* ProgressPlainObject.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA930B6253C8A65007B717A /* ProgressPlainObject.swift */; };
 		2CA9D97720109718007AA743 /* AdaptiveStatsPagerViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA9D97620109718007AA743 /* AdaptiveStatsPagerViewController.swift */; };
 		2CA9D97920109727007AA743 /* AdaptiveStatsPresenter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA9D97820109727007AA743 /* AdaptiveStatsPresenter.swift */; };
 		2CA9D97D20109C07007AA743 /* AdaptiveRatingsPresenter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CA9D97C20109C07007AA743 /* AdaptiveRatingsPresenter.swift */; };
@@ -795,6 +802,7 @@
 		2CF24F67239004D8002DBD0F /* NewStepViewControllerTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CF24F66239004D8002DBD0F /* NewStepViewControllerTests.swift */; };
 		2CF6C4EB244DF619000FAAED /* ARQuickLookStoredFileManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CF6C4EA244DF619000FAAED /* ARQuickLookStoredFileManager.swift */; };
 		2CF7E3342417C1A700B9188E /* UseCellularDataForDownloadsStorageManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CF7E3332417C1A700B9188E /* UseCellularDataForDownloadsStorageManager.swift */; };
+		2CF9BD3C2538508800C2AFD2 /* PromiseKit+Retry.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CF9BD3B2538508800C2AFD2 /* PromiseKit+Retry.swift */; };
 		2CFC5ABC228ADFC400B5248A /* StepsPersistenceService.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CFC5ABB228ADFC400B5248A /* StepsPersistenceService.swift */; };
 		2CFDB1241F559F9A00B8035C /* AvatarImageView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CFDB1231F559F9A00B8035C /* AvatarImageView.swift */; };
 		2CFED65F252C5AC900FCAD41 /* Result+Stepik.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2CFED65E252C5AC900FCAD41 /* Result+Stepik.swift */; };
@@ -2078,6 +2086,14 @@
 		2CA3E8AE24C173C600FA3059 /* CourseInfoTabInfoAboutBlockView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CourseInfoTabInfoAboutBlockView.swift; sourceTree = "<group>"; };
 		2CA47D49248ABF0E00925335 /* LogoutDataClearService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LogoutDataClearService.swift; sourceTree = "<group>"; };
 		2CA51BAF24AB9B4300A400AE /* NewProfileUserActivityViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NewProfileUserActivityViewModel.swift; sourceTree = "<group>"; };
+		2CA9307A253C691F007B717A /* StepPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StepPlainObject.swift; sourceTree = "<group>"; };
+		2CA9307F253C6B03007B717A /* DiscussionThreadPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DiscussionThreadPlainObject.swift; sourceTree = "<group>"; };
+		2CA93087253C79C9007B717A /* AttemptPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AttemptPlainObject.swift; sourceTree = "<group>"; };
+		2CA93090253C86D0007B717A /* VideoURLPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = VideoURLPlainObject.swift; sourceTree = "<group>"; };
+		2CA93098253C8760007B717A /* VideoPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = VideoPlainObject.swift; sourceTree = "<group>"; };
+		2CA930A3253C884F007B717A /* BlockPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BlockPlainObject.swift; sourceTree = "<group>"; };
+		2CA930B6253C8A65007B717A /* ProgressPlainObject.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ProgressPlainObject.swift; sourceTree = "<group>"; };
+		2CA930C8253C9644007B717A /* Model_step_actions_v66.xcdatamodel */ = {isa = PBXFileReference; lastKnownFileType = wrapper.xcdatamodel; path = Model_step_actions_v66.xcdatamodel; sourceTree = "<group>"; };
 		2CA9D97620109718007AA743 /* AdaptiveStatsPagerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdaptiveStatsPagerViewController.swift; sourceTree = "<group>"; };
 		2CA9D97820109727007AA743 /* AdaptiveStatsPresenter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdaptiveStatsPresenter.swift; sourceTree = "<group>"; };
 		2CA9D97C20109C07007AA743 /* AdaptiveRatingsPresenter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdaptiveRatingsPresenter.swift; sourceTree = "<group>"; };
@@ -2233,6 +2249,7 @@
 		2CF6649122F307A500F2A899 /* Model_user_ is_organization.xcdatamodel */ = {isa = PBXFileReference; lastKnownFileType = wrapper.xcdatamodel; path = "Model_user_ is_organization.xcdatamodel"; sourceTree = "<group>"; };
 		2CF6C4EA244DF619000FAAED /* ARQuickLookStoredFileManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ARQuickLookStoredFileManager.swift; sourceTree = "<group>"; };
 		2CF7E3332417C1A700B9188E /* UseCellularDataForDownloadsStorageManager.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = UseCellularDataForDownloadsStorageManager.swift; sourceTree = "<group>"; };
+		2CF9BD3B2538508800C2AFD2 /* PromiseKit+Retry.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "PromiseKit+Retry.swift"; sourceTree = "<group>"; };
 		2CFC5ABB228ADFC400B5248A /* StepsPersistenceService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StepsPersistenceService.swift; sourceTree = "<group>"; };
 		2CFDA8181FBB3CFD0098A441 /* Model_sections_with_course_id_v21.xcdatamodel */ = {isa = PBXFileReference; lastKnownFileType = wrapper.xcdatamodel; path = Model_sections_with_course_id_v21.xcdatamodel; sourceTree = "<group>"; };
 		2CFDB1231F559F9A00B8035C /* AvatarImageView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AvatarImageView.swift; sourceTree = "<group>"; };
@@ -3082,8 +3099,8 @@
 		2C096588236C5727005B771A /* ThirdParty */ = {
 			isa = PBXGroup;
 			children = (
-				2C48D5FB228D865E00739477 /* Guarantee+ThenableWithFallback.swift */,
-				2C4DDADE242FD1A400A0B4C8 /* HTTPHeader+Stepik.swift */,
+				2CF9BD372538504D00C2AFD2 /* Alamofire */,
+				2CF9BD332538503C00C2AFD2 /* PromiseKit */,
 			);
 			path = ThirdParty;
 			sourceTree = "<group>";
@@ -3562,6 +3579,7 @@
 			children = (
 				0800B81A1D06DC1B006C987E /* Comment.swift */,
 				0800B8171D06D961006C987E /* DiscussionProxy.swift */,
+				2CA9307F253C6B03007B717A /* DiscussionThreadPlainObject.swift */,
 				086A8B241D21434B00F45C45 /* Vote.swift */,
 			);
 			path = Discussions;
@@ -4449,6 +4467,15 @@
 			path = StepikVideoPlayerViewController;
 			sourceTree = "<group>";
 		};
+		2CA9308F253C86BD007B717A /* Video */ = {
+			isa = PBXGroup;
+			children = (
+				2CA93098253C8760007B717A /* VideoPlainObject.swift */,
+				2CA93090253C86D0007B717A /* VideoURLPlainObject.swift */,
+			);
+			path = Video;
+			sourceTree = "<group>";
+		};
 		2CA9D98B20122EAF007AA743 /* AdaptiveLeaderboardsNames */ = {
 			isa = PBXGroup;
 			children = (
@@ -4715,6 +4742,23 @@
 			path = ModulesTests;
 			sourceTree = "<group>";
 		};
+		2CF9BD332538503C00C2AFD2 /* PromiseKit */ = {
+			isa = PBXGroup;
+			children = (
+				2C48D5FB228D865E00739477 /* Guarantee+ThenableWithFallback.swift */,
+				2CF9BD3B2538508800C2AFD2 /* PromiseKit+Retry.swift */,
+			);
+			path = PromiseKit;
+			sourceTree = "<group>";
+		};
+		2CF9BD372538504D00C2AFD2 /* Alamofire */ = {
+			isa = PBXGroup;
+			children = (
+				2C4DDADE242FD1A400A0B4C8 /* HTTPHeader+Stepik.swift */,
+			);
+			path = Alamofire;
+			sourceTree = "<group>";
+		};
 		2CFED669252C647900FCAD41 /* TableViewDataSource */ = {
 			isa = PBXGroup;
 			children = (
@@ -5603,13 +5647,18 @@
 		2CFF903F242A2AAA00FD7311 /* PlainObjects */ = {
 			isa = PBXGroup;
 			children = (
+				2CA93087253C79C9007B717A /* AttemptPlainObject.swift */,
+				2CA930A3253C884F007B717A /* BlockPlainObject.swift */,
 				62E98321CB033D7736CD4DDB /* CoursePayment.swift */,
 				2CB3563D2476CB7B00E59A03 /* MagicLink.swift */,
+				2CA930B6253C8A65007B717A /* ProgressPlainObject.swift */,
+				2CA9307A253C691F007B717A /* StepPlainObject.swift */,
 				2CF10C882384243100F8CC95 /* StepSource.swift */,
 				2CB1C3AC240050F9001DA83E /* UserCodeRun.swift */,
 				2CECFEF0252F1F4C006BA883 /* VisitedCourse.swift */,
 				2CA3DAA62179DF7300F43888 /* Discussions */,
 				2C1661012358D3290020B7F4 /* StepOptions */,
+				2CA9308F253C86BD007B717A /* Video */,
 			);
 			path = PlainObjects;
 			sourceTree = "<group>";
@@ -7840,6 +7889,7 @@
 				2C97E00A215E47EC005684A1 /* SearchQueriesPresenter.swift in Sources */,
 				08CA59EA1BBD3D55008DC44D /* UILabelExtensions.swift in Sources */,
 				08FEFC211F127470005CA0FB /* AutocompleteWords.swift in Sources */,
+				2CA93091253C86D0007B717A /* VideoURLPlainObject.swift in Sources */,
 				08484F03211AF4320006266F /* SegmentedProgressView.swift in Sources */,
 				0861E6721CD80A9600B45652 /* Executable.swift in Sources */,
 				083AABE91BE8D63D005E1E96 /* Progress.swift in Sources */,
@@ -7968,6 +8018,7 @@
 				085C4FF31D89C86F00B27C95 /* UnitsAPI.swift in Sources */,
 				0800B8181D06D961006C987E /* DiscussionProxy.swift in Sources */,
 				2CE664E620F5207A0082F3FE /* DownloaderProtocol.swift in Sources */,
+				2CF9BD3C2538508800C2AFD2 /* PromiseKit+Retry.swift in Sources */,
 				0813EEA71BFE5A5400DB4B83 /* Assignment.swift in Sources */,
 				2C06E0B02243CD2D00AF4DA2 /* CourseInfoTabReviewsSkeletonView.swift in Sources */,
 				089877A2214047650065DFA2 /* SplitTestingService.swift in Sources */,
@@ -8046,6 +8097,7 @@
 				2CD846471F25FB6C00E8153C /* Profile+CoreDataProperties.swift in Sources */,
 				087585C01FB524C20047A269 /* ContentLanguage.swift in Sources */,
 				08901E631CD0EDB300D94613 /* RemoteVersionManager.swift in Sources */,
+				2CA930B7253C8A65007B717A /* ProgressPlainObject.swift in Sources */,
 				0828FF7C1BC7F9D7000AFEA7 /* Unit+CoreDataProperties.swift in Sources */,
 				2CD462EA226F4279004E4725 /* FetchResult.swift in Sources */,
 				0800B81B1D06DC1B006C987E /* Comment.swift in Sources */,
@@ -8204,6 +8256,7 @@
 				0869F6D21CE216B600F8A6DB /* PersistentQueueRecoveryManager.swift in Sources */,
 				08CA59F11BBFD65E008DC44D /* User+CoreDataProperties.swift in Sources */,
 				2C23C5E61F6BFA8800FC2B7C /* RegistrationPresenter.swift in Sources */,
+				2CA930A4253C884F007B717A /* BlockPlainObject.swift in Sources */,
 				2C5F77C41F90FC2500E8E175 /* NotificationsMarkAsReadButton.swift in Sources */,
 				2CF7E3342417C1A700B9188E /* UseCellularDataForDownloadsStorageManager.swift in Sources */,
 				086A8B251D21434B00F45C45 /* Vote.swift in Sources */,
@@ -8260,6 +8313,7 @@
 				083F2B171E9D8F1D00714173 /* CertificatesView.swift in Sources */,
 				2C01BB68233CD92C00C8DCF0 /* Require.swift in Sources */,
 				2CC5AA6C242A34C500C09F94 /* RecommendationsAPI.swift in Sources */,
+				2CA93099253C8760007B717A /* VideoPlainObject.swift in Sources */,
 				2C96E11624192ACB005EDE2B /* UIColor+DynamicColor.swift in Sources */,
 				080F31DD1BA7162C00F356A0 /* StepikToken.swift in Sources */,
 				080CE14F1E9562F30089A27F /* StepsAPI.swift in Sources */,
@@ -8439,6 +8493,7 @@
 				62E9860632B3BB21E24DF368 /* SectionsNetworkService.swift in Sources */,
 				62E9851C596D4146AC811EAE /* UnitsNetworkService.swift in Sources */,
 				62E983B402214CA82BF050E8 /* LessonsNetworkService.swift in Sources */,
+				2CA93080253C6B03007B717A /* DiscussionThreadPlainObject.swift in Sources */,
 				2CE9BF44248D07D0004F6659 /* CodeTemplatesPersistenceService.swift in Sources */,
 				2C8F3AE123CCBD26004D113A /* DownloadVideoQuality.swift in Sources */,
 				2CDB95892412C08100F676A7 /* SpotlightContinueUserActivityService.swift in Sources */,
@@ -8513,6 +8568,7 @@
 				62E98B04C8A3F4DFE7F8B00F /* BaseExploreViewController.swift in Sources */,
 				62E9888D488FC62B6F16A332 /* CourseInfoAssembly.swift in Sources */,
 				62E9826776831EAD02AA9A18 /* CourseInfoDataFlow.swift in Sources */,
+				2CA93088253C79C9007B717A /* AttemptPlainObject.swift in Sources */,
 				62E98CBA3A377097538AB3D2 /* CourseInfoHeaderViewModel.swift in Sources */,
 				62E98CE13AF85515F639F07D /* CourseInfoInteractor.swift in Sources */,
 				62E98C6E8D9F16F809760722 /* CourseInfoPresenter.swift in Sources */,
@@ -8791,6 +8847,7 @@
 				62E9833E9BFB4229BFEB4DD5 /* CodeQuizFullscreenPresenter.swift in Sources */,
 				62E98042B4F232FCD9788187 /* CodeQuizFullscreenProvider.swift in Sources */,
 				62E983915F585672BB010B73 /* CodeQuizFullscreenView.swift in Sources */,
+				2CA9307B253C691F007B717A /* StepPlainObject.swift in Sources */,
 				62E98BE715996F6FF7C93EF1 /* CodeQuizFullscreenViewController.swift in Sources */,
 				62E98ED854756E2499392186 /* CodeQuizFullscreenViewModel.swift in Sources */,
 				62E98A9DF433C986B49F7980 /* CodeQuizFullscreenCodeViewController.swift in Sources */,
@@ -10015,6 +10072,7 @@
 		08D1EF6E1BB5618700BE84E6 /* Model.xcdatamodeld */ = {
 			isa = XCVersionGroup;
 			children = (
+				2CA930C8253C9644007B717A /* Model_step_actions_v66.xcdatamodel */,
 				2C36E4772501F28E00D63C41 /* Model_user_remove_level_v65.xcdatamodel */,
 				2C00396424E61B3000EBC7FF /* Model_assignment_progress_id_v64.xcdatamodel */,
 				2CDC9EFB24E516F800916BAE /* Model_course_preview_lesson_id_v63.xcdatamodel */,
@@ -10082,7 +10140,7 @@
 				0802AC531C7222B200C4F3E6 /* Model_v2.xcdatamodel */,
 				08D1EF6F1BB5618700BE84E6 /* Model.xcdatamodel */,
 			);
-			currentVersion = 2C36E4772501F28E00D63C41 /* Model_user_remove_level_v65.xcdatamodel */;
+			currentVersion = 2CA930C8253C9644007B717A /* Model_step_actions_v66.xcdatamodel */;
 			path = Model.xcdatamodeld;
 			sourceTree = "<group>";
 			versionGroupType = wrapper.xcdatamodel;

Stepic/Legacy/Model/AttemptsSumbissions/Datasets/ChoiceDataset.swift

@@ -44,6 +44,13 @@ final class ChoiceDataset: Dataset {
         super.init(coder: coder)
     }
 
+    private override init() {
+        self.isMultipleChoice = false
+        self.options = []
+
+        super.init()
+    }
+
     override func encode(with coder: NSCoder) {
         coder.encode(self.isMultipleChoice, forKey: JSONKey.isMultipleChoice.rawValue)
         coder.encode(self.options, forKey: JSONKey.options.rawValue)
@@ -60,6 +67,13 @@ final class ChoiceDataset: Dataset {
         return true
     }
 
+    override func copy(with zone: NSZone? = nil) -> Any {
+        let copy = ChoiceDataset()
+        copy.isMultipleChoice = self.isMultipleChoice
+        copy.options = self.options
+        return copy
+    }
+
     enum JSONKey: String {
         case isMultipleChoice = "is_multiple_choice"
         case options

Stepic/Legacy/Model/AttemptsSumbissions/Datasets/Dataset.swift

@@ -1,7 +1,7 @@
 import SwiftyJSON
 import Foundation
 
-class Dataset: NSObject, NSCoding {
+class Dataset: NSObject, NSCoding, NSCopying {
     required init(json: JSON) {
         super.init()
     }
@@ -10,5 +10,11 @@ class Dataset: NSObject, NSCoding {
         super.init()
     }
 
+    override init() {
+        super.init()
+    }
+
     func encode(with coder: NSCoder) {}
+
+    func copy(with zone: NSZone? = nil) -> Any { Dataset() }
 }

Stepic/Legacy/Model/AttemptsSumbissions/Datasets/FillBlanksDataset.swift

@@ -57,6 +57,11 @@ final class FillBlanksDataset: Dataset {
         super.init(coder: coder)
     }
 
+    private override init() {
+        self.components = []
+        super.init()
+    }
+
     override func encode(with coder: NSCoder) {
         coder.encode(self.components, forKey: JSONKey.components.rawValue)
     }
@@ -71,12 +76,18 @@ final class FillBlanksDataset: Dataset {
         return true
     }
 
+    override func copy(with zone: NSZone? = nil) -> Any {
+        let copy = FillBlanksDataset()
+        copy.components = self.components.map { $0.copy() as! FillBlanksComponent }
+        return copy
+    }
+
     enum JSONKey: String {
         case components
     }
 }
 
-final class FillBlanksComponent: NSObject, NSCoding {
+final class FillBlanksComponent: NSObject, NSCoding, NSCopying {
     var componentType: ComponentType
     var text: String
     var options: [String]
@@ -118,6 +129,14 @@ final class FillBlanksComponent: NSObject, NSCoding {
         super.init()
     }
 
+    private override init() {
+        self.componentType = .text
+        self.text = ""
+        self.options = []
+
+        super.init()
+    }
+
     func encode(with coder: NSCoder) {
         coder.encode(self.componentType.rawValue, forKey: JSONKey.type.rawValue)
         coder.encode(self.text, forKey: JSONKey.text.rawValue)
@@ -136,6 +155,14 @@ final class FillBlanksComponent: NSObject, NSCoding {
         return true
     }
 
+    func copy(with zone: NSZone? = nil) -> Any {
+        let copy = FillBlanksComponent()
+        copy.componentType = self.componentType
+        copy.text = self.text
+        copy.options = self.options
+        return copy
+    }
+
     private static func sanitizeText(_ text: String) -> String {
         var text = text
 

Stepic/Legacy/Model/AttemptsSumbissions/Datasets/FreeAnswerDataset.swift

@@ -35,6 +35,13 @@ final class FreeAnswerDataset: Dataset {
         super.init(coder: coder)
     }
 
+    private override init() {
+        self.isHTMLEnabled = false
+        self.isAttachmentsEnabled = false
+
+        super.init()
+    }
+
     override func encode(with coder: NSCoder) {
         coder.encode(self.isHTMLEnabled, forKey: JSONKey.isHTMLEnabled.rawValue)
         coder.encode(self.isAttachmentsEnabled, forKey: JSONKey.isAttachmentsEnabled.rawValue)
@@ -51,6 +58,13 @@ final class FreeAnswerDataset: Dataset {
         return true
     }
 
+    override func copy(with zone: NSZone? = nil) -> Any {
+        let copy = FreeAnswerDataset()
+        copy.isHTMLEnabled = self.isHTMLEnabled
+        copy.isAttachmentsEnabled = self.isAttachmentsEnabled
+        return copy
+    }
+
     enum JSONKey: String {
         case isHTMLEnabled = "is_html_enabled"
         case isAttachmentsEnabled = "is_attachments_enabled"

Stepic/Legacy/Model/AttemptsSumbissions/Datasets/MatchingDataset.swift

@@ -57,6 +57,11 @@ final class MatchingDataset: Dataset {
         super.init(coder: coder)
     }
 
+    private override init() {
+        self.pairs = []
+        super.init()
+    }
+
     override func encode(with coder: NSCoder) {
         coder.encode(self.firstValues, forKey: JSONKey.first.rawValue)
         coder.encode(self.secondValues, forKey: JSONKey.second.rawValue)
@@ -73,6 +78,12 @@ final class MatchingDataset: Dataset {
         return true
     }
 
+    override func copy(with zone: NSZone? = nil) -> Any {
+        let copy = MatchingDataset()
+        copy.pairs = self.pairs
+        return copy
+    }
+
     enum JSONKey: String {
         case pairs
         case first