Don't "scroll to bottom" when messages are sent from desktop.

// FREEBIE

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -1704,13 +1704,6 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
     }
 }
 
-- (void)finishSendingMessageAnimated:(BOOL)animated
-{
-    [super finishSendingMessageAnimated:animated];
-
-    [self scrollToBottomAnimated:animated];
-}
-
 - (void)toggleDefaultKeyboard
 {
     // Primary language is nil for the emoji keyboard & we want to stay on it after sending
@@ -3591,6 +3584,17 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
         return;
     }
 
+    BOOL wasAtBottom = [self isScrolledToBottom];
+    // We want sending messages to feel snappy.  So, if the only
+    // update is a new outgoing message AND we're already scrolled to
+    // the bottom of the conversation, skip the scroll animation.
+    __block BOOL shouldAnimateScrollToBottom = !wasAtBottom;
+    // We want to scroll to the bottom if the user:
+    //
+    // a) already was at the bottom of the conversation.
+    // b) is inserting new interactions.
+    __block BOOL scrollToBottom = wasAtBottom;
+
     [self.collectionView performBatchUpdates:^{
         for (YapDatabaseViewRowChange *rowChange in messageRowChanges) {
             switch (rowChange.type) {
@@ -3607,6 +3611,15 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
                 }
                 case YapDatabaseViewChangeInsert: {
                     [self.collectionView insertItemsAtIndexPaths:@[ rowChange.newIndexPath ]];
+
+                    TSInteraction *interaction = [self interactionAtIndexPath:rowChange.newIndexPath];
+                    if ([interaction isKindOfClass:[TSOutgoingMessage class]]) {
+                        TSOutgoingMessage *outgoingMessage = (TSOutgoingMessage *)interaction;
+                        if (!outgoingMessage.isFromLinkedDevice) {
+                            scrollToBottom = YES;
+                            shouldAnimateScrollToBottom = NO;
+                        }
+                    }
                     break;
                 }
                 case YapDatabaseViewChangeMove: {
@@ -3632,6 +3645,10 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
             }
 
             [self updateLastVisibleTimestamp];
+
+            if (scrollToBottom) {
+                [self scrollToBottomAnimated:shouldAnimateScrollToBottom];
+            }
         }];
 }
 

SignalServiceKit/src/Messages/Interactions/TSOutgoingMessage.h

@@ -101,6 +101,9 @@ typedef NS_ENUM(NSInteger, TSGroupMetaMessage) {
 
 @property (nonatomic, readonly) BOOL isVoiceMessage;
 
+// This property won't be accurate for legacy messages.
+@property (atomic, readonly) BOOL isFromLinkedDevice;
+
 /**
  * Signal Identifier (e.g. e164 number) or nil if in a group thread.
  */
@@ -168,6 +171,7 @@ typedef NS_ENUM(NSInteger, TSGroupMetaMessage) {
 - (void)updateWithWasDeliveredWithTransaction:(YapDatabaseReadWriteTransaction *)transaction;
 - (void)updateWithWasDelivered;
 - (void)updateWithWasSentAndDelivered;
+- (void)updateWithWasSentAndDeliveredFromLinkedDevice;
 - (void)updateWithSingleGroupRecipient:(NSString *)singleGroupRecipient
                            transaction:(YapDatabaseReadWriteTransaction *)transaction;
 

SignalServiceKit/src/Messages/Interactions/TSOutgoingMessage.m

@@ -28,6 +28,7 @@ NSString *const kTSOutgoingMessageSentRecipientAll = @"kTSOutgoingMessageSentRec
 @property (atomic) NSString *mostRecentFailureText;
 @property (atomic) BOOL wasDelivered;
 @property (atomic) NSString *singleGroupRecipient;
+@property (atomic) BOOL isFromLinkedDevice;
 
 // For outgoing, non-legacy group messages sent from this client, this
 // contains the list of recipients to whom the message has been sent.
@@ -333,6 +334,18 @@ NSString *const kTSOutgoingMessageSentRecipientAll = @"kTSOutgoingMessageSentRec
     }];
 }
 
+- (void)updateWithWasSentAndDeliveredFromLinkedDevice
+{
+    [self.dbReadWriteConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
+        [self applyChangeToSelfAndLatestOutgoingMessage:transaction
+                                            changeBlock:^(TSOutgoingMessage *message) {
+                                                [message setMessageState:TSOutgoingMessageStateSentToService];
+                                                [message setWasDelivered:YES];
+                                                [message setIsFromLinkedDevice:YES];
+                                            }];
+    }];
+}
+
 - (void)updateWithSingleGroupRecipient:(NSString *)singleGroupRecipient
                            transaction:(YapDatabaseReadWriteTransaction *)transaction
 {

SignalServiceKit/src/Messages/OWSMessageSender.m

@@ -1084,7 +1084,7 @@ NSString *const OWSMessageSenderRateLimitedException = @"RateLimitedException";
 
 - (void)handleMessageSentRemotely:(TSOutgoingMessage *)message sentAt:(uint64_t)sentAt
 {
-    [message updateWithWasSentAndDelivered];
+    [message updateWithWasSentAndDeliveredFromLinkedDevice];
     [self becomeConsistentWithDisappearingConfigurationForMessage:message];
     [OWSDisappearingMessagesJob setExpirationForMessage:message expirationStartedAt:sentAt];
 }