public BirthdayEditViewModel(
            ICommandResolver commandResolver,
            INavigationService navigationService,
            IFileSystem fileService,
            IMediaService mediaService,
            IPlatformDocumentPicker documentPicker)
            : base(navigationService)
        {
            _fileService             = fileService;
            _mediaService            = mediaService;
            SaveBirthdayCommand      = commandResolver.AsyncCommand(SaveBirthday);
            ChangePersonImageCommand = commandResolver.AsyncCommand(ChangePersonImage);
            SelectMonthCommand       = commandResolver.Command <BirthDateViewModel>(SelectMonth);
            SelectDayCommand         = commandResolver.Command <BirthdayDayViewModel>(SelectDay);
            _documentPicker          = documentPicker;

            BirthDateViewModels = new RangeObservableCollection <BirthDateViewModel>();
            InitializeDays();
            SelectedBirthDateViewModel = BirthDateViewModels.ElementAt(0);
        }