使用 IsolatedStorageSettings 在 wp8 中永久存储应用程序的信息

我正在使用IsolatedStorageSettings在我的应用程序中存储密钥的联系人列表。但是应用程序只存储列表，直到应用程序处于活动状态(即从一个页面导航到另一个页面(。如果我退出应用程序并再次重新启动它，则找不到存储的密钥/联系人列表。如何在安装应用之前永久保存应用的列表？这是我的视图模型的代码，我正在使用：

   public class ContactsViewModel : ViewModelBase
    {
        private static IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;
        private List<SavedContact> _SavedContactsList;
        public ContactsViewModel()
        {
            Contacts cons = new Contacts();
            cons.SearchAsync(String.Empty, FilterKind.None, null);
            cons.SearchCompleted += new EventHandler<ContactsSearchEventArgs>(OnContactSearchCompleted);
            SaveSavedContactsCommand = new RelayCommand(OnSaveSavedContacts);
        }

        private List<SavedContact> GetSavedContacts()
        {
            if (appSettings.Contains("SavedContacts"))
            {
                var savedContacts = (List<SavedContact>)appSettings["SavedContacts"];
                return savedContacts;
            }
            else
            {
                return new List<SavedContact>();
            }
        }
        public RelayCommand SaveSavedContactsCommand { get; set; }
        private void OnSaveSavedContacts()
        {
            if (!SavedContactsList.Any(x => x.IsSelected == true))
            {
                MessageBox.Show("Please select some contacts and then click on Save button.");
            }
            else
            {
                var selectedSavedContacts = SavedContactsList.Where(x => x.IsSelected == true).ToList();
                SavedContacts = selectedSavedContacts;
                MessageBox.Show("Emergency contact list added successfully.");
                App.RootFrame.GoBack();
            }
        }
        void OnContactSearchCompleted(object sender, ContactsSearchEventArgs e)
        {
            try
            {
                SavedContactsList = new List<SavedContact>();
                var allContacts = new List<Contact>(e.Results.Where(x => x.PhoneNumbers.Count() > 0).OrderBy(c => c.DisplayName));
                // var savedContacts = GetSavedContacts();
                var savedContacts = SavedContacts;
                foreach (Contact contact in allContacts)
                {
                    SavedContact SavedContact = new SavedContact() { Contact = contact };
                    if (savedContacts.Any(x => x.Contact.PhoneNumbers.ElementAt(0).PhoneNumber == contact.PhoneNumbers.ElementAt(0).PhoneNumber))
                    {
                        SavedContact.IsSelected = true;
                    }
                    else
                    {
                        SavedContact.IsSelected = false;
                    }
                    SavedContactsList.Add(SavedContact);
                }
            }
            catch (System.Exception ex)
            {
                MessageBox.Show("Error in retrieving contacts : " + ex.Message);
            }
        }
        [DataMember]
        public List<SavedContact> SavedContactsList
        {
            get { return _SavedContactsList; }
            set
            {
                _SavedContactsList = value;
                RaisePropertyChanged("SavedContactsList");
            }
        }
        private List<SavedContact> SavedContacts
        {
            get
            {
                if (appSettings.Contains("SavedContacts"))
                {
                    var savedContacts = (List<SavedContact>)appSettings["SavedContacts"];
                    return savedContacts;
                }
                else
                {
                    return new List<SavedContact>();
                }
            }
            set
            {
                appSettings["SavedContacts"] = value;
            }
        }

    }

保存联系人类如下：

  [DataContract]
    public class SavedContact : INotifyPropertyChanged
    {
        public SavedContact() { }
        private bool _isSelected;
        private Contact _contact;
        [DataMember]
        public bool IsSelected
        {
            get
            {
                return _isSelected;
            }
            set
            {
                if (_isSelected != value)
                {
                    _isSelected = value;
                    OnPropertyChanged("IsSelected");
                }
            }
        }
        [DataMember]
        public Contact Contact
        {
            get
            {
                return _contact;
            }
            set
            {
                if (_contact != value)
                {
                    _contact = value;
                    OnPropertyChanged("Contact");
                }
            }
        }
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

视图模型绑定到<toolKit: LongListMultiSelector />的位置。功能就像，我从长名单多重选择器中选择一些联系人并将其保存在存储中以供以后重复使用。但是如果我退出应用程序并重新启动它，保存的联系人将返回空。当我在应用程序中导航其他页面时，正在打印保存的联系人。如果我第一次保存列表，在应用程序重新启动时，GetSavedContacts(( 会返回一个新列表。