Decompose MessagesViewController, add “scroll to bottom button”, improve scrolling behavior.

// FREEBIE

Signal/src/ViewControllers/MessagesViewController.h

@@ -6,6 +6,7 @@
 #import <MediaPlayer/MediaPlayer.h>
 #import <JSQMessagesViewController/JSQMessagesViewController.h>
 #import "TSGroupModel.h"
+
 @class TSThread;
 
 extern NSString *const OWSMessagesViewControllerDidAppearNotification;
@@ -28,18 +29,14 @@ extern NSString *const OWSMessagesViewControllerDidAppearNotification;
 
 #pragma mark -
 
-@interface MessagesViewController : JSQMessagesViewController <UIImagePickerControllerDelegate,
+@interface MessagesViewController : JSQMessagesViewController
-                                                               UINavigationControllerDelegate,
-                                                               UITextViewDelegate,
-                                                               AVAudioPlayerDelegate,
-                                                               UIGestureRecognizerDelegate>
-
 
 @property (nonatomic, readonly) TSThread *thread;
 
 - (void)configureForThread:(TSThread *)thread
     keyboardOnViewAppearing:(BOOL)keyboardAppearing
         callOnViewAppearing:(BOOL)callOnViewAppearing;
+
 - (void)popKeyBoard;
 
 #pragma mark 3D Touch Methods

Signal/src/util/ThreadUtil.h

@@ -2,19 +2,19 @@
 //  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
 //
 
-@class TSThread;
+NS_ASSUME_NONNULL_BEGIN
+
+@class OWSBlockingManager;
+@class OWSContactsManager;
 @class OWSMessageSender;
 @class SignalAttachment;
 @class TSContactThread;
+@class TSInteraction;
 @class TSStorageManager;
-@class OWSContactsManager;
+@class TSThread;
-@class OWSBlockingManager;
-
-NS_ASSUME_NONNULL_BEGIN
-
 @class TSUnreadIndicatorInteraction;
 
-@interface ThreadOffersAndIndicators : NSObject
+@interface ThreadDynamicInteractions : NSObject
 
 // If there are unseen messages in the thread, this is the index
 // of the unseen indicator, counting from the _end_ of the conversation
@@ -30,23 +30,27 @@ NS_ASSUME_NONNULL_BEGIN
 //
 // Once we enter messages view, we mark all messages read, so we need
 // a snapshot of what the first unread message was when we entered the
-// view so that we can call ensureThreadOffersAndIndicators:...
+// view so that we can call ensureDynamicInteractionsForThread:...
 // repeatedly. The unread indicator should continue to show up until
 // it has been cleared, at which point hideUnreadMessagesIndicator is
-// YES in ensureThreadOffersAndIndicators:...
+// YES in ensureDynamicInteractionsForThread:...
 @property (nonatomic, nullable) NSNumber *firstUnseenInteractionTimestamp;
 
+- (void)clearUnreadIndicatorState;
+
 @end
 
 #pragma mark -
 
+@class TSOutgoingMessage;
+
 @interface ThreadUtil : NSObject
 
-+ (void)sendMessageWithText:(NSString *)text
++ (TSOutgoingMessage *)sendMessageWithText:(NSString *)text
                                   inThread:(TSThread *)thread
                              messageSender:(OWSMessageSender *)messageSender;
 
-+ (void)sendMessageWithAttachment:(SignalAttachment *)attachment
++ (TSOutgoingMessage *)sendMessageWithAttachment:(SignalAttachment *)attachment
                                         inThread:(TSThread *)thread
                                    messageSender:(OWSMessageSender *)messageSender;
 
@@ -68,7 +72,7 @@ NS_ASSUME_NONNULL_BEGIN
 //   slow and unwieldy.  This number represents the maximum current
 //   size of the "load window" in that view. The unread indicator should
 //   always be inserted within that window.
-+ (ThreadOffersAndIndicators *)ensureThreadOffersAndIndicators:(TSThread *)thread
++ (ThreadDynamicInteractions *)ensureDynamicInteractionsForThread:(TSThread *)thread
                                                    storageManager:(TSStorageManager *)storageManager
                                                   contactsManager:(OWSContactsManager *)contactsManager
                                                   blockingManager:(OWSBlockingManager *)blockingManager

Signal/src/util/ThreadUtil.m

@@ -18,7 +18,13 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
-@implementation ThreadOffersAndIndicators
+@implementation ThreadDynamicInteractions
+
+- (void)clearUnreadIndicatorState
+{
+    self.unreadIndicatorPosition = nil;
+    self.firstUnseenInteractionTimestamp = nil;
+}
 
 @end
 
@@ -26,7 +32,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 @implementation ThreadUtil
 
-+ (void)sendMessageWithText:(NSString *)text inThread:(TSThread *)thread messageSender:(OWSMessageSender *)messageSender
++ (TSOutgoingMessage *)sendMessageWithText:(NSString *)text
+                                  inThread:(TSThread *)thread
+                             messageSender:(OWSMessageSender *)messageSender
 {
     OWSAssert([NSThread isMainThread]);
     OWSAssert(text.length > 0);
@@ -48,10 +56,12 @@ NS_ASSUME_NONNULL_BEGIN
         failure:^(NSError *error) {
             DDLogWarn(@"%@ Failed to deliver message with error: %@", self.tag, error);
         }];
+
+    return message;
 }
 
 
-+ (void)sendMessageWithAttachment:(SignalAttachment *)attachment
++ (TSOutgoingMessage *)sendMessageWithAttachment:(SignalAttachment *)attachment
                                         inThread:(TSThread *)thread
                                    messageSender:(OWSMessageSender *)messageSender
 {
@@ -79,9 +89,11 @@ NS_ASSUME_NONNULL_BEGIN
         failure:^(NSError *error) {
             DDLogError(@"%@ Failed to send message attachment with error: %@", self.tag, error);
         }];
+
+    return message;
 }
 
-+ (ThreadOffersAndIndicators *)ensureThreadOffersAndIndicators:(TSThread *)thread
++ (ThreadDynamicInteractions *)ensureDynamicInteractionsForThread:(TSThread *)thread
                                                    storageManager:(TSStorageManager *)storageManager
                                                   contactsManager:(OWSContactsManager *)contactsManager
                                                   blockingManager:(OWSBlockingManager *)blockingManager
@@ -96,7 +108,7 @@ NS_ASSUME_NONNULL_BEGIN
     OWSAssert(blockingManager);
     OWSAssert(maxRangeSize > 0);
 
-    ThreadOffersAndIndicators *result = [ThreadOffersAndIndicators new];
+    ThreadDynamicInteractions *result = [ThreadDynamicInteractions new];
 
     [storageManager.dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
         const int kMaxBlockOfferOutgoingMessageCount = 10;
@@ -141,7 +153,7 @@ NS_ASSUME_NONNULL_BEGIN
                           } else if ([object isKindOfClass:[TSErrorMessage class]]) {
                               TSErrorMessage *errorMessage = (TSErrorMessage *)object;
                               OWSAssert(errorMessage.errorType == TSErrorMessageNonBlockingIdentityChange);
-                              [nonBlockingSafetyNumberChanges addObject:object];
+                              [nonBlockingSafetyNumberChanges addObject:errorMessage];
                           } else {
                               DDLogError(@"Unexpected interaction type: %@", [object class]);
                               OWSAssert(0);
@@ -165,6 +177,7 @@ NS_ASSUME_NONNULL_BEGIN
                 firstUnseenInteractionTimestamp = @(firstUnseenInteraction.timestampForSorting);
             }
         }
+        result.firstUnseenInteractionTimestamp = firstUnseenInteractionTimestamp;
 
         TSIncomingMessage *firstIncomingMessage =
             [[transaction ext:TSThreadIncomingMessageDatabaseViewExtensionName] firstObjectInGroup:thread.uniqueId];
@@ -183,7 +196,7 @@ NS_ASSUME_NONNULL_BEGIN
         __block BOOL hasMoreUnseenMessages = NO;
         __block TSInteraction *interactionAfterUnreadIndicator = nil;
         NSUInteger missingUnseenSafetyNumberChangeCount = 0;
-        if (firstUnseenInteractionTimestamp) {
+        if (firstUnseenInteractionTimestamp != nil) {
             [[transaction ext:TSMessageDatabaseViewExtensionName]
                 enumerateRowsInGroup:thread.uniqueId
                          withOptions:NSEnumerationReverse
@@ -199,13 +212,13 @@ NS_ASSUME_NONNULL_BEGIN
                                   return;
                               }
 
-                              if ([object isKindOfClass:[TSUnreadIndicatorInteraction class]]) {
+                              TSInteraction *interaction = (TSInteraction *)object;
-                                  // Ignore existing unread indicator, if any.
+
+                              if (interaction.isDynamicInteraction) {
+                                  // Ignore dynamic interactions, if any.
                                   return;
                               }
 
-                              TSInteraction *interaction = (TSInteraction *)object;
-
                               if (interaction.timestampForSorting
                                   < firstUnseenInteractionTimestamp.unsignedLongLongValue) {
                                   // By default we want the unread indicator to appear just before
@@ -251,7 +264,6 @@ NS_ASSUME_NONNULL_BEGIN
                     = (missingUnseenSafetyNumberChanges.count + nonBlockingSafetyNumberChanges.count);
             }
         }
-        result.firstUnseenInteractionTimestamp = firstUnseenInteractionTimestamp;
         if (hasMoreUnseenMessages) {
             // The unread indicator is _before_ the last visible unseen message.
             result.unreadIndicatorPosition = @(visibleUnseenMessageCount);