Some improvement to observing user changes.

platform-darwin/Source/MPAppDelegate_Store.h

@@ -35,6 +35,7 @@ typedef NS_ENUM( NSUInteger, MPImportResult ) {
 + (BOOL)managedObjectContextForMainThreadPerformBlockAndWait:(void ( ^ )(NSManagedObjectContext *mainContext))mocBlock;
 + (BOOL)managedObjectContextPerformBlock:(void ( ^ )(NSManagedObjectContext *context))mocBlock;
 + (BOOL)managedObjectContextPerformBlockAndWait:(void ( ^ )(NSManagedObjectContext *context))mocBlock;
++ (id)managedObjectContextChanged:(void ( ^ )(NSDictionary<NSManagedObjectID *, NSString *> *affectedObjects))changedBlock;
 
 - (MPFixableResult)findAndFixInconsistenciesSaveInContext:(NSManagedObjectContext *)context;
 - (void)deleteAndResetStore;

platform-darwin/Source/MPAppDelegate_Store.m

@@ -131,6 +131,25 @@ PearlAssociatedObjectProperty( NSNumber*, StoreCorrupted, storeCorrupted );
     return YES;
 }
 
++ (id)managedObjectContextChanged:(void ( ^ )(NSDictionary<NSManagedObjectID *, NSString *> *affectedObjects))changedBlock {
+
+    NSManagedObjectContext *privateManagedObjectContextIfReady = [[self get] privateManagedObjectContextIfReady];
+    if (!privateManagedObjectContextIfReady)
+        return nil;
+
+    return PearlAddNotificationObserver( NSManagedObjectContextObjectsDidChangeNotification, privateManagedObjectContextIfReady, nil,
+            ^(id host, NSNotification *note) {
+                NSMutableDictionary *affectedObjects = [NSMutableDictionary new];
+                for (NSManagedObject *object in note.userInfo[NSInsertedObjectsKey])
+                    affectedObjects[object.objectID] = NSInsertedObjectsKey;
+                for (NSManagedObject *object in note.userInfo[NSUpdatedObjectsKey])
+                    affectedObjects[object.objectID] = NSUpdatedObjectsKey;
+                for (NSManagedObject *object in note.userInfo[NSDeletedObjectsKey])
+                    affectedObjects[object.objectID] = NSDeletedObjectsKey;
+                changedBlock( affectedObjects );
+            } );
+}
+
 - (NSManagedObjectContext *)mainManagedObjectContextIfReady {
 
     [self loadStore];
@@ -196,13 +215,15 @@ PearlAssociatedObjectProperty( NSNumber*, StoreCorrupted, storeCorrupted );
 
         self.mainManagedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
         self.mainManagedObjectContext.parentContext = self.privateManagedObjectContext;
-
+        if ([self.mainManagedObjectContext respondsToSelector:@selector( automaticallyMergesChangesFromParent )]) // iOS 10+
+            self.mainManagedObjectContext.automaticallyMergesChangesFromParent = YES;
+        else
             // When privateManagedObjectContext is saved, import the changes into mainManagedObjectContext.
             PearlAddNotificationObserverTo( self.mainManagedObjectContext, NSManagedObjectContextDidSaveNotification,
-                self.privateManagedObjectContext, nil, ^(NSManagedObjectContext *mainManagedObjectContext, NSNotification *note) {
+                    self.privateManagedObjectContext, nil, ^(NSManagedObjectContext *mainContext, NSNotification *note) {
-            [mainManagedObjectContext performBlock:^{
+                [mainContext performBlock:^{
                     @try {
-                    [mainManagedObjectContext mergeChangesFromContextDidSaveNotification:note];
+                        [mainContext mergeChangesFromContextDidSaveNotification:note];
                     }
                     @catch (NSException *exception) {
                         err( @"While merging changes:\n%@", [exception fullDescription] );

platform-darwin/Source/MPEntities.m

@@ -16,7 +16,7 @@
 - (BOOL)saveToStore {
 
     __block BOOL success = YES;
-    if ([self hasChanges]) {
+    if ([self hasChanges])
         [self performBlockAndWait:^{
             @try {
                 NSError *error = nil;
@@ -28,7 +28,6 @@
                 err( @"While saving: %@", [exception fullDescription] );
             }
         }];
-    }
 
     return success && (!self.parentContext || [self.parentContext saveToStore]);
 }

platform-darwin/Source/iOS/MPUsersViewController.m

@@ -58,6 +58,7 @@ typedef NS_ENUM( NSUInteger, MPActiveUserState ) {
 @implementation MPUsersViewController {
     NSString *_masterPasswordChoice;
     NSOperationQueue *_afterUpdates;
+    __weak id _contextChangedObserver;
 }
 
 - (void)viewDidLoad {
@@ -90,15 +91,6 @@ typedef NS_ENUM( NSUInteger, MPActiveUserState ) {
     self.userSelectionContainer.visible = NO;
 }
 
-- (void)viewWillDisappear:(BOOL)animated {
-
-    [super viewWillDisappear:animated];
-
-    PearlRemoveNotificationObservers();
-
-    [self.marqueeTipTimer invalidate];
-}
-
 - (void)viewDidAppear:(BOOL)animated {
 
     [super viewDidAppear:animated];
@@ -130,6 +122,15 @@ typedef NS_ENUM( NSUInteger, MPActiveUserState ) {
         ((MPWebViewController *)segue.destinationViewController).initialURL = [NSURL URLWithString:@"http://thanks.lhunath.com"];
 }
 
+- (void)viewWillDisappear:(BOOL)animated {
+
+    [super viewWillDisappear:animated];
+
+    [self removeObservers];
+
+    [self.marqueeTipTimer invalidate];
+}
+
 #pragma mark - UITextFieldDelegate
 
 - (void)textFieldDidEndEditing:(UITextField *)textField {
@@ -465,25 +466,23 @@ referenceSizeForFooterInSection:(NSInteger)section {
 - (void)deleteUser:(NSManagedObjectID *)userID {
 
     [MPiOSAppDelegate managedObjectContextPerformBlock:^(NSManagedObjectContext *context) {
-        MPUserEntity
+        MPUserEntity *user = [MPUserEntity existingObjectWithID:userID inContext:context];
-                *user_ = [MPUserEntity existingObjectWithID:userID inContext:context];
+        if (!user)
-        if (!user_)
             return;
 
-        [context deleteObject:user_];
+        [context deleteObject:user];
         [context saveToStore];
-        [self reloadUsers]; // I do NOT understand why our ObjectsDidChangeNotification isn't firing on saveToStore.
     }];
 }
 
 - (void)resetUser:(NSManagedObjectID *)userID avatar:(MPAvatarCell *)avatarCell {
 
     [MPiOSAppDelegate managedObjectContextPerformBlock:^(NSManagedObjectContext *context) {
-        MPUserEntity *user_ = [MPUserEntity existingObjectWithID:userID inContext:context];
+        MPUserEntity *user = [MPUserEntity existingObjectWithID:userID inContext:context];
-        if (!user_)
+        if (!user)
             return;
 
-        [[MPiOSAppDelegate get] changeMasterPasswordFor:user_ saveInContext:context didResetBlock:^{
+        [[MPiOSAppDelegate get] changeMasterPasswordFor:user saveInContext:context didResetBlock:^{
             PearlMainQueue( ^{
                 NSIndexPath *avatarIndexPath = [self.avatarCollectionView indexPathForCell:avatarCell];
                 [self.avatarCollectionView selectItemAtIndexPath:avatarIndexPath animated:NO
@@ -645,15 +644,21 @@ referenceSizeForFooterInSection:(NSInteger)section {
     }];
 }
 
-- (void)registerObservers {
+- (void)removeObservers {
 
     [self removeKeyPathObservers];
+    PearlRemoveNotificationObservers();
+    [[NSNotificationCenter defaultCenter] removeObserver:_contextChangedObserver];
+}
+
+- (void)registerObservers {
+
+    [self removeObservers];
     [self observeKeyPath:@"avatarCollectionView.contentOffset" withBlock:
             ^(id from, id to, NSKeyValueChange cause, MPUsersViewController *_self) {
                 [_self updateAvatarVisibility];
             }];
 
-    PearlRemoveNotificationObservers();
     PearlAddNotificationObserver( UIApplicationDidEnterBackgroundNotification, nil, [NSOperationQueue mainQueue],
             ^(MPUsersViewController *self, NSNotification *note) {
                 self.userSelectionContainer.visible = NO;
@@ -675,37 +680,32 @@ referenceSizeForFooterInSection:(NSInteger)section {
                 [self.keyboardHeightConstraint updateConstant:keyboardHeight];
             } );
 
-    NSManagedObjectContext *mainContext = [MPiOSAppDelegate managedObjectContextForMainThreadIfReady];
+    if ((_contextChangedObserver = [MPiOSAppDelegate managedObjectContextChanged:^(NSDictionary<NSManagedObjectID *, NSString *> *affectedObjects) {
-    [UIView animateWithDuration:0.3f animations:^{
+        if ([[[affectedObjects allKeys] filteredArrayUsingPredicate:
-        self.avatarCollectionView.visible = mainContext != nil;
+                [NSPredicate predicateWithBlock:^BOOL(NSManagedObjectID *objectID, NSDictionary *bindings) {
-    }];
+                    return [objectID.entity.name isEqualToString:NSStringFromClass( [MPUserEntity class] )];
-    if (mainContext && self.storeLoadingActivity.isAnimating)
-        [self.storeLoadingActivity stopAnimating];
-    if (!mainContext && !self.storeLoadingActivity.isAnimating)
-        [self.storeLoadingActivity startAnimating];
-
-    if (mainContext)
-        PearlAddNotificationObserver( NSManagedObjectContextObjectsDidChangeNotification, mainContext, nil,
-                ^(MPUsersViewController *self, NSNotification *note) {
-                    NSSet *insertedObjects = note.userInfo[NSInsertedObjectsKey];
-                    NSSet *deletedObjects = note.userInfo[NSDeletedObjectsKey];
-                    if ([[NSSetUnion( insertedObjects, deletedObjects )
-                            filteredSetUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings) {
-                                return [evaluatedObject isKindOfClass:[MPUserEntity class]];
                 }]] count])
             [self reloadUsers];
-                } );
+    }]))
+        [UIView animateWithDuration:0.3f animations:^{
+            self.avatarCollectionView.visible = YES;
+            [self.storeLoadingActivity stopAnimating];
+        }];
+    else
+        [UIView animateWithDuration:0.3f animations:^{
+            self.avatarCollectionView.visible = NO;
+            [self.storeLoadingActivity startAnimating];
+        }];
+
     PearlAddNotificationObserver( NSPersistentStoreCoordinatorStoresWillChangeNotification, [MPiOSAppDelegate get].storeCoordinator, nil,
             ^(MPUsersViewController *self, NSNotification *note) {
                 self.userIDs = nil;
             } );
     PearlAddNotificationObserver( NSPersistentStoreCoordinatorStoresDidChangeNotification, [MPiOSAppDelegate get].storeCoordinator, nil,
             ^(MPUsersViewController *self, NSNotification *note) {
-                PearlMainQueue( ^{
                 [self registerObservers];
                 [self reloadUsers];
             } );
-            } );
 }
 
 - (void)reloadUsers {