Fetching Contacts From People Hub - windows-phone-8

Question

I am building a Windows Phone 8 application. For that I require to fetch contacts from People Hub App. Is there any way I can keep these contacts even after the application closes?
I have looked into data caching but if the contact has been updated then caching won't work.

Answer 1

This can be done.
I've implemented this with the Group Contacts app.
In my solution, I used SQLite to store contacts into various categories based on user preference.
When the app starts up, I initialize my local database using SQLite and pull contacts from there as well as retrieving all the contacts the phone itself.
Example:
await ContactsRepository.Instance.Initialize();
var appContacts = await ContactsRepository.Instance.Get();
var phoneContacts = await ContactServices.Instance.LoadContacts(Contacts, SelectedCategory);
MergeContacts(appContacts, phoneContacts);
.
.
When ever the app starts up, it needs to create a database if one does not already exist.
Example:
public async Task Initialize()
{
_connection = new SQLiteAsyncConnection(Constants.DATABASE_FILE_NAME);
await EnsureTableExist<ContactReference>(_connection);
}
private async Task EnsureTableExist<T>(SQLiteAsyncConnection connection) where T : new()
{
bool noTableExists = false;
try
{
var query = await connection.Table<T>().FirstOrDefaultAsync();
}
catch (SQLiteException ex)
{
if (ex.Message.Contains("no such table"))
{
noTableExists = true;
}
}
if (noTableExists)
{
await connection.CreateTableAsync<T>();
}
}
Windows 8.1 uses a ContactManager to retrieve contacts from the People Hub.
Example:
public async Task<ObservableCollection<Contact>> LoadContacts(ObservableCollection<Contact> contacts, Category category)
{
contacts.Clear();
try
{
var contactStore = await ContactManager.RequestStoreAsync();
var result = await contactStore.FindContactsAsync();
foreach (var item in result)
{
contacts.Add(item);
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
return contacts;
}
Then I manage my contact collection between the phone's contact list and my app's contact list.
Example:
private void MergeContacts(ObservableCollection<ContactReference> appContacts, ObservableCollection<Contact> phoneContacts)
{
foreach (var contact in phoneContacts)
{
var contactExists = appContacts.Any(c => c.ContactId == contact.Id);
if (!contactExists)
{
OthersCategory.Contacts.Add(contact);
}
Category category = GetCategory(contact);
if (category == null)
{
OthersCategory.Contacts.Add(contact);
}
}
SortContacts(OthersCategory);
}
I created an entity class to support my local database operations.
Example:
public class ContactReference
{
[PrimaryKey]
public string ContactId { get; set; }
public string CategoryName { get; set; }
}
NOTE:
The emulator that VS2013 provides does not have a list of imaginary contacts.
As a result, I found testing easier by using my personal phone for debugging.