OnNavigatedTo in Prism不会触发其中一个页面

Question

我面对的是OnNavigatedTo在Prism中的奇怪行为。它总是在Android上运行，但在iOS上它不适用于其中一个页面。见代码：

private void OnSpecialtyTapped()
        {
            _navigationService.NavigateAsync($"{nameof(SpecialtyFilterPage)}", useModalNavigation: false);
        }

private void OnLocationTapped()
        {
            _navigationService.NavigateAsync($"{nameof(PlacesFilterPage)}", useModalNavigation: false);
        }


private void OnTakeChosenSpecialties()
        {
            var parameters = new NavigationParameters
            {
                //{"ChosenSpecialtiesIds", CheckedSpecialties.Select(s => s.Id).ToList()}
            };

            _navigationService.GoBackAsync(parameters);
        }

private void OnTakeChosenPlaces()
        {
            var parameters = new NavigationParameters
            {
                //{"ChosenPlaces", CheckedPlaces.Select( p => new Models.PlaceParameter {Id=p.Id, Type=Convert.ToString(p.Type)}).ToList()}
            };

            _navigationService.GoBackAsync(parameters);
        }

public void OnNavigatedTo(NavigationParameters parameters)
        {
            if ( parameters.ContainsKey("ChosenSpecialtiesIds") )
            {
                var chosenSpecialtiestIds = parameters["ChosenSpecialtiesIds"] as List<string>;
                if ( chosenSpecialtiestIds == null ) return;
                _filter.Services.Clear();

                foreach ( var specialtiestId in chosenSpecialtiestIds )
                {
                    _filter.Services.Add(new ServiceParameter { Id = specialtiestId });
                }
            }
            else if ( parameters.ContainsKey("ChosenPlaces") )
            {
                var chosenPlaces = parameters["ChosenPlaces"] as List<PlaceParameter>;
                if ( chosenPlaces == null ) return;
                _filter.Places.Clear();

                _filter.Places = chosenPlaces;
            }

        }

它适用于Specialty，不适用于带有Places的iOS。我正在使用Prism 6.2.0和Xamarin.Forms 2.3.3.193。由于某些错误，我无法使用更新的版本。