show the detailed info of SSK group update

SignalServiceKit/src/Loki/Protocol/Closed Groups/ClosedGroupsProtocol.swift

@@ -124,7 +124,8 @@ public final class ClosedGroupsProtocol : NSObject {
         let newGroupModel = TSGroupModel(title: name, memberIds: members, image: nil, groupId: groupID, groupType: .closedGroup, adminIds: admins)
         thread.setGroupModel(newGroupModel, with: transaction)
         // Notify the user
-        let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: .typeGroupUpdate)
+        let updateInfo = group.getInfoStringAboutUpdate(to: newGroupModel, contactsManager: SSKEnvironment.shared.contactsManager)
+        let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: .typeGroupUpdate, customMessage: updateInfo)
         infoMessage.save(with: transaction)
     }
 
@@ -206,7 +207,8 @@ public final class ClosedGroupsProtocol : NSObject {
         thread.setGroupModel(newGroupModel, with: transaction)
         // Notify the user
         let infoMessageType: TSInfoMessageType = isUserLeaving ? .typeGroupQuit : .typeGroupUpdate
-        let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: infoMessageType)
+        let updateInfo = group.getInfoStringAboutUpdate(to: newGroupModel, contactsManager: SSKEnvironment.shared.contactsManager)
+        let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: infoMessageType, customMessage: updateInfo)
         infoMessage.save(with: transaction)
         // Return
         return promise
@@ -347,7 +349,8 @@ public final class ClosedGroupsProtocol : NSObject {
         // Notify the user if needed (don't notify them if the message just contained linked device sender keys)
         if Set(members) != Set(oldMembers) || Set(admins) != Set(group.groupAdminIds) || name != group.groupName {
             let infoMessageType: TSInfoMessageType = wasUserRemoved ? .typeGroupQuit : .typeGroupUpdate
-            let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: infoMessageType)
+            let updateInfo = group.getInfoStringAboutUpdate(to: newGroupModel, contactsManager: SSKEnvironment.shared.contactsManager)
+            let infoMessage = TSInfoMessage(timestamp: NSDate.ows_millisecondTimeStamp(), in: thread, messageType: infoMessageType, customMessage: updateInfo)
             infoMessage.save(with: transaction)
         }
     }

SignalServiceKit/src/Messages/TSGroupModel.m

@@ -133,7 +133,7 @@ const int32_t kGroupIdLength = 16;
 
     if ([membersWhoLeft count] > 0) {
         NSArray *oldMembersNames = [[membersWhoLeft allObjects] map:^NSString*(NSString* item) {
-            return [contactsManager displayNameForPhoneIdentifier:item];
+            return [LKUserDisplayNameUtilities getPrivateChatDisplayNameFor:item];
         }];
         updatedGroupInfoString = [updatedGroupInfoString
                                   stringByAppendingString:[NSString