fix admin check method

Signal/src/ViewControllers/ThreadSettings/UpdateGroupViewController.m

@@ -385,7 +385,6 @@ NS_ASSUME_NONNULL_BEGIN
                                                            groupId:self.thread.groupModel.groupId
                                                          groupType:self.thread.groupModel.groupType
                                                           adminIds:self.thread.groupModel.groupAdminIds];
-    groupModel.removedMembers = self.removedRecipientIds;
     [self.conversationSettingsViewDelegate groupWasUpdated:groupModel];
 }
 

SignalServiceKit/src/Contacts/Threads/TSGroupThread.h

@@ -39,6 +39,7 @@ extern NSString *const TSGroupThread_NotificationKey_UniqueId;
 - (BOOL)isLocalUserInGroup;
 - (BOOL)isLocalUserInGroupWithTransaction:(YapDatabaseReadTransaction *)transaction;
 - (BOOL)isUserInGroup:(NSString *)hexEncodedPublicKey transaction:(YapDatabaseReadWriteTransaction *)transaction;
+- (BOOL)isUserAdminForGroup:(NSString *)hexEncodedPublicKey transaction:(YapDatabaseReadWriteTransaction *)transaction;
 
 // all group threads containing recipient as a member
 + (NSArray<TSGroupThread *> *)groupThreadsWithRecipientId:(NSString *)recipientId

SignalServiceKit/src/Contacts/Threads/TSGroupThread.m

@@ -211,6 +211,13 @@ NSString *const TSGroupThread_NotificationKey_UniqueId = @"TSGroupThread_Notific
     return [linkedDeviceHexEncodedPublicKeys intersectsSet:[NSSet setWithArray:self.groupModel.groupMemberIds]];
 }
 
+- (BOOL)isUserAdminForGroup:(NSString *)hexEncodedPublicKey transaction:(YapDatabaseReadWriteTransaction *)transaction
+{
+    if (hexEncodedPublicKey == nil) { return NO; }
+    NSSet<NSString *> *linkedDeviceHexEncodedPublicKeys = [LKDatabaseUtilities getLinkedDeviceHexEncodedPublicKeysFor:hexEncodedPublicKey in:transaction];
+    return [linkedDeviceHexEncodedPublicKeys intersectsSet:[NSSet setWithArray:self.groupModel.groupAdminIds]];
+}
+
 - (NSString *)name
 {
     // TODO sometimes groupName is set to the empty string. I'm hesitent to change

SignalServiceKit/src/Messages/OWSMessageManager.m

@@ -1024,6 +1024,8 @@ NS_ASSUME_NONNULL_BEGIN
                                                                           messageType:TSInfoMessageTypeGroupUpdate
                                                                         customMessage:updateMessage];
                 [infoMessage saveWithTransaction:transaction];
+                // Loki: if there is a update of group members, we should establish a session with the new members.
+                [self establishSessionsWithMembersIfNeeded:newGroupModel.groupMemberIds forThread:newGroupThread transaction:transaction];
             } else if (transcript.isGroupQuit) {
                 TSGroupThread *groupThread = [TSGroupThread getOrCreateThreadWithGroupId:transcript.dataMessage.group.id groupType:closedGroup transaction:transaction];
                 [groupThread leaveGroupWithTransaction:transaction];
@@ -1477,7 +1479,7 @@ NS_ASSUME_NONNULL_BEGIN
 
         switch (dataMessage.group.type) {
             case SSKProtoGroupContextTypeUpdate: {
-                if (oldGroupThread && ![oldGroupThread.groupModel.groupAdminIds containsObject:hexEncodedPublicKey]) {
+                if (oldGroupThread && ![oldGroupThread isUserAdminForGroup:hexEncodedPublicKey transaction:transaction]) {
                     [LKLogger print:[NSString stringWithFormat:@"[Loki] Received a group update from a non-admin user for %@; ignoring.", [LKGroupUtilities getEncodedGroupID:groupId]]];
                     return nil;
                 }