ReadContact.txt

//permissions need
	<uses-permission android:name="android.permission.READ_CONTACTS" />

//code
        void FillContacts()
        {
            var uri = ContactsContract.Contacts.ContentUri;
            string[] projection = {
       ContactsContract.Contacts.InterfaceConsts.Id,
       ContactsContract.Contacts.InterfaceConsts.DisplayName,
       ContactsContract.Contacts.InterfaceConsts.PhotoId
  };
            // CursorLoader introduced in Honeycomb (3.0, API11)
            var loader = new CursorLoader(this, uri, projection, null, null, null);
            var cursor = (ICursor)loader.LoadInBackground();
            List<Contact> contactList = new List<Contact>();
            if (cursor.MoveToFirst())
            {
                do
                {
                    contactList.Add(
                    new Contact( cursor.GetLong(cursor.GetColumnIndex(projection[0])),
                         cursor.GetString(cursor.GetColumnIndex(projection[1])),
                       cursor.GetString(cursor.GetColumnIndex(projection[2]))
                   )
                   );
                } while (cursor.MoveToNext());
            }

        }

        class Contact
        {    long Id;
            string DisplayName;
            string PhotoId;
           public  Contact(long Id, string DisplayName,string PhotoId)
            {
                this.Id = Id;
                this.DisplayName = DisplayName;
                this.PhotoId = PhotoId;
            }
        }