c# - How to make a global property that is visible within all pages in a Windows 10 app? -

i thinking of app represents store, using gridview view items , data represented observablecollection.

my xaml code :

xmlns:data="using:itemsstore.models"  <gridview itemssource="{x:bind itemslist}">         <gridview.itemtemplate>             <datatemplate x:datatype="data:item">                                      <stackpanel orientation="vertical">                         <image source="{x:bind imagesource}"/>                        <textblock  text="{x:bind name}"/>                        <textblock  text="{x:bind disc}"/>                      </stackpanel>             </datatemplate>         </gridview.itemtemplate> </gridview> 

the c# code in mainpage :

public sealed partial class mainpage : page {     public observablecollection<item> itemslist;      public mainpage()     {         this.initializecomponent();          itemslist = new observablecollection<item>();      } } 

i added button , input controls add new items itemslist , works fine, want make page contains controls , logic add new items list, made addnew.xaml page couldn't access observablecollection in mainpage add new items it, , tried make observablecollection static field , managed access collection in mainpage saw no change in mainpage after updating collection in addnew page.

i think problem because of initializing statement in mainpage constructor , every time navigate addnew page , update collection , navigate mainpage constrctor gets called , collection reset, solution making observablecollection golbal variable , initializing somewhere out of mainpage constructor , or initialze collection within event handler excutes once when app launces.

so questions : 1- there way make global observablecollection visible every page in app ? if so, how can refrence in binding statement (x:bind theglobalcollection) or

2- there event trigged once through app life time ?

i sorry big question, time.

if understood correct, remove instatiation constructor , change field this:

public static observablecollection<item> itemslist = new observablecollection<item>();

in way, itemslist instantiated once.