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Signal/src/ViewControllers/ConversationView/Cells/OWSMessageCell.m

@@ -38,6 +38,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 @property (nonatomic) BOOL isPresentingMenuController;
 
+@property (nonatomic, readonly) OWSMessageCellType messageCellType;
+
 @end
 
 #pragma mark -
@@ -59,6 +61,8 @@ NS_ASSUME_NONNULL_BEGIN
     // Ensure only called once.
     OWSAssertDebug(!self.messageBubbleView);
 
+    _messageCellType = OWSMessageCellType_Unknown;
+
     self.layoutMargins = UIEdgeInsetsZero;
     self.contentView.layoutMargins = UIEdgeInsetsZero;
 
@@ -119,11 +123,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 #pragma mark - Convenience Accessors
 
-- (OWSMessageCellType)cellType
-{
-    return self.viewItem.messageCellType;
-}
-
 - (TSMessage *)message
 {
     OWSAssertDebug([self.viewItem.interaction isKindOfClass:[TSMessage class]]);
@@ -152,9 +151,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (OWSMessageView *)messageView
 {
-    if (self.cellType == OWSMessageCellType_StickerMessage) {
+    if (self.messageCellType == OWSMessageCellType_StickerMessage) {
         return self.messageStickerView;
-    } else if (self.cellType == OWSMessageCellType_ViewOnce) {
+    } else if (self.messageCellType == OWSMessageCellType_ViewOnce) {
         return self.messageViewOnceView;
     } else {
         return self.messageBubbleView;
@@ -180,6 +179,21 @@ NS_ASSUME_NONNULL_BEGIN
     self.sendFailureBadgeView.hidden = !self.shouldHaveSendFailureBadge;
 }
 
+- (void)setViewItem:(nullable id<ConversationViewItem>)viewItem
+{
+    OWSAssertIsOnMainThread();
+
+    [super setViewItem:viewItem];
+
+    if (viewItem) {
+        if (!self.hasPreparedForDisplay) {
+            _messageCellType = viewItem.messageCellType;
+        } else {
+            OWSAssertDebug(self.messageCellType == viewItem.messageCellType);
+        }
+    }
+}
+
 // This will only ever be called *once* and should prepare for displaying a specific
 // type of message cell. Future reused cells will always use the same type.
 - (void)prepareForDisplay
@@ -640,7 +654,7 @@ NS_ASSUME_NONNULL_BEGIN
     // Right now, only stickers need the reply button to fade in.
     // If we add other message types that don't have bubbles,
     // we should add them here.
-    return self.cellType == OWSMessageCellType_StickerMessage;
+    return self.messageCellType == OWSMessageCellType_StickerMessage;
 }
 
 - (void)setIsReplyActive:(BOOL)isReplyActive

Signal/src/ViewControllers/ConversationView/Cells/OWSMessageCell.swift

@@ -6,24 +6,6 @@ import Foundation
 
 @objc
 extension OWSMessageCell {
-    var messageCellType: OWSMessageCellType {
-        if let viewItem = viewItem { return viewItem.messageCellType }
-
-        // If accessed before the reuseIdentifier is defined, we don't know
-        // what type of thing this is. In practice, this will only happen
-        // while we're measuring the cell in which case we have nothing to
-        // really cleanup. TODO: maybe should fail here sometimes.
-        guard let reuseIdentifier = reuseIdentifier else { return .unknown }
-
-        let components = reuseIdentifier.split(separator: "-")
-        guard components.count == 3 else {
-            owsFailDebug("unexpected reuseIdentifier")
-            return .unknown
-        }
-
-        return OWSMessageCellType(stringValue: String(components[1]))
-    }
-
     class func cellReuseIdentifier(forMessageCellType cellType: OWSMessageCellType, isOutgoingMessage: Bool) -> String {
         // We use dashes instead of underscores as separators here since `OWSMessageCellType`
         // stringValue contains underscores.

Signal/src/ViewControllers/ConversationView/ConversationViewItem.m

@@ -538,13 +538,13 @@ NSString *NSStringForViewOnceMessageState(ViewOnceMessageState cellType)
 
     // For performance reasons, we cache one instance of each kind of
     // cell and uses these cells for measurement.
-    static NSMutableDictionary<NSNumber *, ConversationViewCell *> *measurementCellCache = nil;
+    static NSMutableDictionary<NSString *, ConversationViewCell *> *measurementCellCache = nil;
     static dispatch_once_t onceToken;
     dispatch_once(&onceToken, ^{
         measurementCellCache = [NSMutableDictionary new];
     });
 
-    NSNumber *cellCacheKey = @(self.interaction.interactionType);
+    NSString *cellCacheKey = self.cellReuseIdentifier;
     ConversationViewCell *_Nullable measurementCell = measurementCellCache[cellCacheKey];
     if (!measurementCell) {
         switch (self.interaction.interactionType) {
@@ -616,12 +616,9 @@ NSString *NSStringForViewOnceMessageState(ViewOnceMessageState cellType)
     }
 }
 
-- (ConversationViewCell *)dequeueCellForCollectionView:(UICollectionView *)collectionView
-                                             indexPath:(NSIndexPath *)indexPath
+- (nullable NSString *)cellReuseIdentifier
 {
     OWSAssertIsOnMainThread();
-    OWSAssertDebug(collectionView);
-    OWSAssertDebug(indexPath);
     OWSAssertDebug(self.interaction);
 
     switch (self.interaction.interactionType) {
@@ -629,41 +626,43 @@ NSString *NSStringForViewOnceMessageState(ViewOnceMessageState cellType)
             OWSFailDebug(@"Unknown interaction type.");
             return nil;
         case OWSInteractionType_IncomingMessage:
-            return [collectionView
-                dequeueReusableCellWithReuseIdentifier:[OWSMessageCell
-                                                           cellReuseIdentifierForMessageCellType:self.messageCellType
-                                                                               isOutgoingMessage:NO]
-                                          forIndexPath:indexPath];
+            return [OWSMessageCell cellReuseIdentifierForMessageCellType:self.messageCellType isOutgoingMessage:NO];
         case OWSInteractionType_OutgoingMessage:
-            return [collectionView
-                dequeueReusableCellWithReuseIdentifier:[OWSMessageCell
-                                                           cellReuseIdentifierForMessageCellType:self.messageCellType
-                                                                               isOutgoingMessage:YES]
-                                          forIndexPath:indexPath];
+            return [OWSMessageCell cellReuseIdentifierForMessageCellType:self.messageCellType isOutgoingMessage:YES];
         case OWSInteractionType_Error:
         case OWSInteractionType_Info:
         case OWSInteractionType_Call:
-            return [collectionView dequeueReusableCellWithReuseIdentifier:[OWSSystemMessageCell cellReuseIdentifier]
-                                                             forIndexPath:indexPath];
+            return [OWSSystemMessageCell cellReuseIdentifier];
         case OWSInteractionType_Offer:
-            return [collectionView dequeueReusableCellWithReuseIdentifier:[OWSContactOffersCell cellReuseIdentifier]
-                                                             forIndexPath:indexPath];
+            return [OWSContactOffersCell cellReuseIdentifier];
 
         case OWSInteractionType_TypingIndicator:
-            return [collectionView dequeueReusableCellWithReuseIdentifier:[OWSTypingIndicatorCell cellReuseIdentifier]
-                                                             forIndexPath:indexPath];
+            return [OWSTypingIndicatorCell cellReuseIdentifier];
         case OWSInteractionType_ThreadDetails:
-            return [collectionView dequeueReusableCellWithReuseIdentifier:[OWSThreadDetailsCell cellReuseIdentifier]
-                                                             forIndexPath:indexPath];
+            return [OWSThreadDetailsCell cellReuseIdentifier];
         case OWSInteractionType_UnreadIndicator:
-            return [collectionView dequeueReusableCellWithReuseIdentifier:[OWSUnreadIndicatorCell cellReuseIdentifier]
-                                                             forIndexPath:indexPath];
+            return [OWSUnreadIndicatorCell cellReuseIdentifier];
         case OWSInteractionType_DateHeader:
-            return [collectionView dequeueReusableCellWithReuseIdentifier:[OWSDateHeaderCell cellReuseIdentifier]
-                                                             forIndexPath:indexPath];
+            return [OWSDateHeaderCell cellReuseIdentifier];
     }
 }
 
+- (ConversationViewCell *)dequeueCellForCollectionView:(UICollectionView *)collectionView
+                                             indexPath:(NSIndexPath *)indexPath
+{
+    OWSAssertIsOnMainThread();
+    OWSAssertDebug(collectionView);
+    OWSAssertDebug(indexPath);
+
+    NSString *_Nullable cellReuseIdentifier = self.cellReuseIdentifier;
+    if (!cellReuseIdentifier) {
+        OWSFailDebug(@"Unknown cell type.");
+        return nil;
+    }
+
+    return [collectionView dequeueReusableCellWithReuseIdentifier:cellReuseIdentifier forIndexPath:indexPath];
+}
+
 - (nullable TSAttachmentStream *)firstValidAlbumAttachment
 {
     OWSAssertDebug(self.mediaAlbumItems.count > 0);