Add documentation

Session/Conversations/ConversationVC+Interaction.swift

@@ -92,6 +92,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
     }
     
     func handleLibraryButtonTapped() {
+        // FIXME: We're not yet handling the case where the user only gives access to selected photos/videos
         guard requestLibraryPermissionIfNeeded() else { return }
         let sendMediaNavController = SendMediaNavigationController.showingMediaLibraryFirst()
         sendMediaNavController.sendMediaNavDelegate = self
@@ -122,7 +123,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
     }
 
     func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) {
-        SNAppearance.switchToSessionAppearance()
+        SNAppearance.switchToSessionAppearance() // Switch back to the correct appearance
     }
 
     func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) {
@@ -337,6 +338,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
 
     // MARK: View Item Interaction
     func handleViewItemLongPressed(_ viewItem: ConversationViewItem) {
+        // Show the context menu if applicable
         guard let index = viewItems.firstIndex(where: { $0 === viewItem }),
             let cell = messagesTableView.cellForRow(at: IndexPath(row: index, section: 0)) as? VisibleMessageCell,
             let snapshot = cell.bubbleView.snapshotView(afterScreenUpdates: false), contextMenuWindow == nil,
@@ -363,6 +365,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
 
     func handleViewItemTapped(_ viewItem: ConversationViewItem, gestureRecognizer: UITapGestureRecognizer) {
         if let message = viewItem.interaction as? TSOutgoingMessage, message.messageState == .failed {
+            // Show the failed message sheet
             showFailedMessageSheet(for: message)
         } else {
             switch viewItem.messageCellType {
@@ -371,12 +374,14 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
                 guard let index = viewItems.firstIndex(where: { $0 === viewItem }),
                     let cell = messagesTableView.cellForRow(at: IndexPath(row: index, section: 0)) as? VisibleMessageCell, let albumView = cell.albumView else { return }
                 let locationInCell = gestureRecognizer.location(in: cell)
+                // Figure out whether the "read more" button was tapped
                 if let overlayView = cell.mediaTextOverlayView {
                     let locationInOverlayView = cell.convert(locationInCell, to: overlayView)
                     if let readMoreButton = overlayView.readMoreButton, readMoreButton.frame.contains(locationInOverlayView) {
-                        return showFullText(viewItem) // FIXME: Bit of a hack to do it this way
+                        return showFullText(viewItem) // HACK: This is a dirty way to do this
                     }
                 }
+                // Otherwise, figure out which of the media views was tapped
                 let locationInAlbumView = cell.convert(locationInCell, to: albumView)
                 guard let mediaView = albumView.mediaView(forLocation: locationInAlbumView) else { return }
                 if albumView.isMoreItemsView(mediaView: mediaView) && viewItem.mediaAlbumHasFailedAttachment() {
@@ -392,13 +397,16 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
                 let gallery = MediaGallery(thread: thread, options: [ .sliderEnabled, .showAllMediaButton ])
                 gallery.presentDetailView(fromViewController: self, mediaAttachment: stream)
             case .genericAttachment:
+                // Open the document if possible
                 guard let url = viewItem.attachmentStream?.originalMediaURL else { return }
                 let shareVC = UIActivityViewController(activityItems: [ url ], applicationActivities: nil)
                 navigationController!.present(shareVC, animated: true, completion: nil)
             case .textOnlyMessage:
                 if let preview = viewItem.linkPreview, let urlAsString = preview.urlString, let url = URL(string: urlAsString) {
+                    // Open the link preview URL
                     openURL(url)
                 } else if let reply = viewItem.quotedReply {
+                    // Scroll to the source of the reply
                     guard let indexPath = viewModel.ensureLoadWindowContainsQuotedReply(reply) else { return }
                     messagesTableView.scrollToRow(at: indexPath, at: UITableView.ScrollPosition.middle, animated: true)
                 }
@@ -436,7 +444,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
 
     func handleViewItemDoubleTapped(_ viewItem: ConversationViewItem) {
         switch viewItem.messageCellType {
-        case .audio: speedUpAudio(for: viewItem)
+        case .audio: speedUpAudio(for: viewItem) // The user can double tap a voice message when it's playing to speed it up
         default: break
         }
     }
@@ -466,6 +474,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
     }
     
     func copySessionID(_ viewItem: ConversationViewItem) {
+        // FIXME: Copying media
         guard let message = viewItem.interaction as? TSIncomingMessage else { return }
         UIPasteboard.general.string = message.authorId
     }
@@ -497,6 +506,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
     }
     
     func openURL(_ url: URL) {
+        // URLs can be unsafe, so always ask the user whether they want to open one
         let urlModal = URLModal(url: url)
         urlModal.modalPresentationStyle = .overFullScreen
         urlModal.modalTransitionStyle = .crossDissolve
@@ -509,6 +519,7 @@ extension ConversationVC : InputViewDelegate, MessageCellDelegate, ContextMenuAc
 
     // MARK: Voice Message Playback
     @objc func handleAudioDidFinishPlayingNotification(_ notification: Notification) {
+        // Play the next voice message if there is one
         guard let audioPlayer = audioPlayer, let viewItem = audioPlayer.owner as? ConversationViewItem,
             let index = viewItems.firstIndex(where: { $0 === viewItem }), index < (viewItems.endIndex - 1) else { return }
         let nextViewItem = viewItems[index + 1]

Session/Conversations/ConversationVC.swift

@@ -1,14 +1,13 @@
 
-// TODO
-// • Slight paging glitch
-// • Photo rounding
-// • Scroll button behind mentions view
+// TODO:
+// • Slight paging glitch when scrolling up and loading more content
+// • Photo rounding (the small corners don't have the correct rounding)
 // • Remaining search glitchiness
 
 final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversationSettingsViewDelegate, ConversationSearchControllerDelegate, UITableViewDataSource, UITableViewDelegate {
     let thread: TSThread
-    let focusedMessageID: String?
-    var didConstrainScrollButton = false
+    let focusedMessageID: String? // This isn't actually used ATM
+    var didConstrainScrollButton = false // Part of a workaround to get the scroll button to show up in the right place
     // Search
     var isShowingSearchUI = false
     var lastSearchedText: String?
@@ -42,11 +41,14 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
         }
     }
 
+    /// The height of the visible part of the table view, i.e. the distance from the navigation bar (where the table view's origin is)
+    /// to the top of the input view (`messagesTableView.adjustedContentInset.bottom`).
     var tableViewUnobscuredHeight: CGFloat {
         let bottomInset = messagesTableView.adjustedContentInset.bottom
         return messagesTableView.bounds.height - bottomInset
     }
 
+    /// The offset at which the table view is exactly scrolled to the bottom.
     var lastPageTop: CGFloat {
         return messagesTableView.contentSize.height - tableViewUnobscuredHeight
     }
@@ -107,7 +109,9 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
     }()
     
     // MARK: Settings
+    /// The table view's bottom inset (content will have this distance to the bottom if the table view is fully scrolled down).
     static let bottomInset = Values.mediumSpacing
+    /// The table view will start loading more content when the content offset becomes less than this.
     static let loadMoreThreshold: CGFloat = 120
     /// The button will be fully visible once the user has scrolled this amount from the bottom of the table view.
     static let scrollButtonFullVisibilityThreshold: CGFloat = 80
@@ -162,6 +166,7 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
     override func viewDidLayoutSubviews() {
         super.viewDidLayoutSubviews()
         if !didFinishInitialLayout {
+            // Scroll to the last unread message if possible; otherwise scroll to the bottom.
             var unreadCount: UInt = 0
             Storage.read { transaction in
                 unreadCount = self.thread.unreadMessageCount(transaction: transaction)
@@ -244,8 +249,8 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
     @objc func handleKeyboardWillChangeFrameNotification(_ notification: Notification) {
         guard let newHeight = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue.size.height else { return }
         if !didConstrainScrollButton {
-            // Bit of a hack to do this here, but it works out.
-            scrollButton.pin(.bottom, to: .bottom, of: view, withInset: -(newHeight + 16))
+            // HACK: Part of a workaround to get the scroll button to show up in the right place
+            scrollButton.pin(.bottom, to: .bottom, of: view, withInset: -(newHeight + 16)) // + 16 to match the bottom inset of the table view
             didConstrainScrollButton = true
         }
         let shouldScroll = (newHeight > 200) // Arbitrary value that's higher than the collapsed size and lower than the expanded size
@@ -266,12 +271,11 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
     }
     
     func conversationViewModelWillUpdate() {
-        
+        // Not currently in use
     }
     
     func conversationViewModelDidUpdate(_ conversationUpdate: ConversationUpdate) {
         guard self.isViewLoaded else { return }
-        // TODO: Reload the thread if it's a group thread?
         let updateType = conversationUpdate.conversationUpdateType
         guard updateType != .minor else { return } // No view items were affected
         if updateType == .reload {
@@ -298,11 +302,9 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
             }
         }
         let batchUpdatesCompletion: (Bool) -> Void = { isFinished in
-            // TODO: Update last visible sort ID?
             if shouldScrollToBottom {
                 self.scrollToBottom(isAnimated: true)
             }
-            // TODO: Update last known distance from bottom
         }
         if shouldAnimate {
             messagesTableView.performBatchUpdates(batchUpdates, completion: batchUpdatesCompletion)
@@ -327,11 +329,11 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
                 }
             }
         }
-        // TODO: Set last reload date?
     }
     
     func conversationViewModelWillLoadMoreItems() {
         view.layoutIfNeeded()
+        // The scroll distance to bottom will be restored in conversationViewModelDidLoadMoreItems
         scrollDistanceToBottomBeforeUpdate = messagesTableView.contentSize.height - messagesTableView.contentOffset.y
     }
     
@@ -343,19 +345,19 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
     }
     
     func conversationViewModelDidLoadPrevPage() {
-        
+        // Not currently in use
     }
     
     func conversationViewModelRangeDidChange() {
-        
+        // Not currently in use
     }
     
     func conversationViewModelDidReset() {
-        
+        // Not currently in use
     }
     
     @objc private func handleGroupUpdatedNotification() {
-        thread.reload()
+        thread.reload() // Needed so that thread.isCurrentUserMemberInGroup() is up to date
         reloadInputViews()
     }
     
@@ -398,7 +400,6 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
         let firstContentPageTop: CGFloat = 0
         let contentOffsetY = max(firstContentPageTop, lastPageTop)
         messagesTableView.setContentOffset(CGPoint(x: 0, y: contentOffsetY), animated: isAnimated)
-        // TODO: Did scroll to bottom
     }
     
     func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
@@ -430,14 +431,14 @@ final class ConversationVC : BaseVC, ConversationViewModelDelegate, OWSConversat
     }
     
     func groupWasUpdated(_ groupModel: TSGroupModel) {
-        // Do nothing
+        // Not currently in use
     }
     
     // MARK: Search
     func conversationSettingsDidRequestConversationSearch(_ conversationSettingsViewController: OWSConversationSettingsViewController) {
         showSearchUI()
         popAllConversationSettingsViews {
-            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { // Without this delay the search bar doesn't show
                 self.searchController.uiSearchController.searchBar.becomeFirstResponder()
             }
         }

Session/Conversations/Input View/InputView.swift

@@ -52,6 +52,10 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
     }()
     
     private lazy var inputTextView: InputTextView = {
+        // HACK: When restoring a draft the input text view won't have a frame yet, and therefore it won't
+        // be able to calculate what size it should be to accommodate the draft text. As a workaround, we
+        // just calculate the max width that the input text view is allowed to be and pass it in. See
+        // setUpViewHierarchy() for why these values are the way they are.
         let adjustment = (InputViewButton.expandedSize - InputViewButton.size) / 2
         let maxWidth = UIScreen.main.bounds.width - 2 * InputViewButton.expandedSize - 2 * Values.smallSpacing - 2 * (Values.mediumSpacing - adjustment)
         return InputTextView(delegate: self, maxWidth: maxWidth)
@@ -134,12 +138,16 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
         delegate.inputTextViewDidChangeContent(inputTextView)
     }
 
+    // We want to show either a link preview or a quote draft, but never both at the same time. When trying to
+    // generate a link preview, wait until we're sure that we'll be able to build a link preview from the given
+    // URL before removing the quote draft.
+    
     private func handleQuoteDraftChanged() {
         additionalContentContainer.subviews.forEach { $0.removeFromSuperview() }
         linkPreviewInfo = nil
         guard let quoteDraftInfo = quoteDraftInfo else { return }
         let direction: QuoteView.Direction = quoteDraftInfo.isOutgoing ? .outgoing : .incoming
-        let hInset: CGFloat = 6
+        let hInset: CGFloat = 6 // Slight visual adjustment
         let maxWidth = additionalContentContainer.bounds.width
         let quoteView = QuoteView(for: quoteDraftInfo.model, direction: direction, hInset: hInset, maxWidth: maxWidth, delegate: self)
         additionalContentContainer.addSubview(quoteView)
@@ -200,6 +208,7 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
     
     // MARK: Interaction
     override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
+        // Needed so that the user can tap the buttons when the expanding attachments button is expanded
         let buttonContainers = [ attachmentsButton.mainButton, attachmentsButton.cameraButton,
             attachmentsButton.libraryButton, attachmentsButton.documentButton, attachmentsButton.gifButton ]
         let buttonContainer = buttonContainers.first { $0.superview!.convert($0.frame, to: self).contains(point) }
@@ -215,8 +224,10 @@ final class InputView : UIView, InputViewButtonDelegate, InputTextViewDelegate,
             attachmentsButton.libraryButtonContainer, attachmentsButton.cameraButtonContainer, attachmentsButton.mainButtonContainer ]
         let isPointInsideAttachmentsButton = buttonContainers.contains { $0.superview!.convert($0.frame, to: self).contains(point) }
         if isPointInsideAttachmentsButton {
+            // Needed so that the user can tap the buttons when the expanding attachments button is expanded
             return true
         } else if mentionsViewContainer.frame.contains(point) {
+            // Needed so that the user can tap mentions
             return true
         } else {
             return super.point(inside: point, with: event)

Session/Conversations/Input View/InputViewButton.swift

@@ -93,6 +93,9 @@ final class InputViewButton : UIView {
     }
     
     // MARK: Interaction
+    
+    // We want to detect both taps and long presses
+    
     override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
         UIImpactFeedbackGenerator(style: .heavy).impactOccurred()
         expand()

Session/Conversations/Message Cells/Content Views/MediaTextOverlayView.swift

@@ -1,4 +1,5 @@
 
+/// Shown over a media message if it has a message body.
 final class MediaTextOverlayView : UIView {
     private let viewItem: ConversationViewItem
     private let albumViewWidth: CGFloat

Session/Conversations/Message Cells/Content Views/QuoteView.swift

@@ -122,6 +122,12 @@ final class QuoteView : UIView {
     }
 
     private func setUpViewHierarchy() {
+        // There's quite a bit of calculation going on here. It's a bit complex so don't make changes
+        // if you don't need to. If you do then test:
+        // • Quoted text in both private chats and group chats
+        // • Quoted images and videos in both private chats and group chats
+        // • Quoted voice messages and documents in both private chats and group chats
+        // • All of the above in both dark mode and light mode
         let hasAttachments = !attachments.isEmpty
         let thumbnailSize = QuoteView.thumbnailSize
         let iconSize = QuoteView.iconSize

Session/Conversations/Message Cells/VisibleMessageCell.swift

@@ -396,14 +396,16 @@ final class VisibleMessageCell : MessageCell, LinkPreviewViewDelegate {
     }
     
     override func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
-        return true
+        return true // Needed for the pan gesture recognizer to work with the table view's pan gesture recognizer
     }
     
     override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
         if gestureRecognizer == panGestureRecognizer {
             let v = panGestureRecognizer.velocity(in: self)
+            // Only allow swipes to the left; allowing swipes to the right gets in the way of the default
+            // iOS swipe to go back gesture
             guard v.x < 0 else { return false }
-            return abs(v.x) > abs(v.y)
+            return abs(v.x) > abs(v.y) // It has to be more horizontal than vertical
         } else {
             return true
         }
@@ -435,13 +437,14 @@ final class VisibleMessageCell : MessageCell, LinkPreviewViewDelegate {
         let translationX = gestureRecognizer.translation(in: self).x.clamp(-CGFloat.greatestFiniteMagnitude, 0)
         switch gestureRecognizer.state {
         case .changed:
+            // The idea here is to asymptotically approach a maximum drag distance
             let damping: CGFloat = 20
             let sign: CGFloat = -1
             let x = (damping * (sqrt(abs(translationX)) / sqrt(damping))) * sign
             viewsToMove.forEach { $0.transform = CGAffineTransform(translationX: x, y: 0) }
             replyButton.alpha = abs(translationX) / VisibleMessageCell.maxBubbleTranslationX
             if abs(translationX) > VisibleMessageCell.swipeToReplyThreshold && abs(previousX) < VisibleMessageCell.swipeToReplyThreshold {
-                UIImpactFeedbackGenerator(style: .heavy).impactOccurred()
+                UIImpactFeedbackGenerator(style: .heavy).impactOccurred() // Let the user know when they've hit the swipe to reply threshold
             }
             previousX = translationX
         case .ended, .cancelled:
@@ -566,6 +569,10 @@ final class VisibleMessageCell : MessageCell, LinkPreviewViewDelegate {
     }
     
     static func getBodyTextView(for viewItem: ConversationViewItem, with availableWidth: CGFloat, textColor: UIColor, searchText: String?, delegate: UITextViewDelegate & BodyTextViewDelegate) -> UITextView {
+        // Take care of:
+        // • Highlighting mentions
+        // • Linkification
+        // • Highlighting search results
         guard let message = viewItem.interaction as? TSMessage else { preconditionFailure() }
         let isOutgoing = (message.interactionType() == .outgoingMessage)
         let result = BodyTextView(snDelegate: delegate)