xf_searchBarwithListViewModel.cs

    #region Fields
            private ObservableCollection<object> _Items;
            private ObservableCollection<object> _ItemsFiltered;
            private ObservableCollection<object> _ItemsUnfiltered;
            private string _searchText;
    #endregion
    
    #region Properties
            public string SearchText
            {
                get { return _searchText; }
                set
                {
                    _searchText = value;
                    OnPropertyChanged("SearchText");
                }
            }
            public ObservableCollection<object>  Items
            {
                get { return _Items; }
                set
                {
                    _Items = value;
                    OnPropertyChanged("Items");
                }
            }
    #endregion
    
    #region Commands
            public ICommand SearchCommand { get; private set; }
    #endregion
    
    #region Constructor
            public  ItemsViewModel()
            {
                Items = new ObservableCollection<object>();
                GetItems(); 
                SearchCommand = new Command(PerformSearch);
            }
     #endregion
     
     #region Methods
    		public void PerformSearch()
            {
                if (string.IsNullOrWhiteSpace(this._searchText))
                    Items = _ItemsUnfiltered;
                else
                {
                    _ItemsFiltered = new ObservableCollection<object>(_ItemsUnfiltered.Where(i =>
                   (i is ItemObj && (((ItemObj)i).ItemObjName.ToLower().Contains(_searchText.ToLower())));
                    Items = _ItemsFiltered;
                }
            }
      #endregion