public ChatMessagesViewModel(
            IImagePickerService imagePicker,
            IPageNavigationService pageNavigationService,
            IChatLocalizedStrings localizedStrings,
            IFormatService formatService,
            ChatManager chatManager,
            ConnectionStatusViewModel connectionStatusViewModel)
        {
            _imagePicker           = imagePicker;
            _pageNavigationService = pageNavigationService;
            _localizedStrings      = localizedStrings;
            _formatService         = formatService;
            _chatManager           = chatManager;

            ConnectionStatus = connectionStatusViewModel;

            BackCommand     = new RelayCommand(_pageNavigationService.GoBack, () => _pageNavigationService.CanGoBack);
            ShowInfoCommand = new RelayCommand(ShowInfo);
        }
        public ChatsListViewModel(
            IPageNavigationService pageNavigationService,
            IDialogsService dialogsService,
            IChatLocalizedStrings localizedStrings,
            IChatsListManager chatsListManager,
            ConnectionStatusViewModel connectionStatusViewModel)
        {
            _pageNavigationService = pageNavigationService;
            _dialogsService        = dialogsService;
            _chatsListManager      = chatsListManager;

            LocalizedStrings          = localizedStrings;
            ConnectionStatusViewModel = connectionStatusViewModel;

            Chats = _chatsListManager.ChatsCollection;

            CreateChatCommand = new RelayCommand(CreateChat);
            LeaveChatCommand  = new AsyncCommand <ChatSummaryViewModel>(LeaveChatAsync);
            DeleteChatCommand = new AsyncCommand <ChatSummaryViewModel>(DeleteChatAsync);
        }