ios - ViewModel is null during ViewDidLoad -

i getting started mvvmcross in ios.

public class mainview : mvxtabbarviewcontroller {     public override void viewdidload()     {         base.viewdidload();          var vm = (mainviewmodel)this.viewmodel;         if (vm == null)             return;     } } 

setting breakpoint line access viewmodel, shows me, viewmodel null.

i can workaround calling viewdidload() in constructor. then, viewmodel null during constructor call, valid in default viewdidload call. looks workaround. can help?

i'm guessing here problem here specific way tabbarviewcontroller constructed.

viewdidload virtual method , called first time view accessed.

in case of tabbarviewcontroller happens during ios base view constructor - i.e. occurs before class has had constructor called.

the way around i've found add check against situation in viewdidload, , make second call viewdidload during class constructor.

you can see in action n-25 - https://github.com/mvvmcross/nplus1daysofmvvmcross/blob/976ede3aafd3a7c6e06717ee48a9a45f08eedcd0/n-25-tabbed/tabbed.touch/views/firstview.cs#l17

something like:

public class mainview : mvxtabbarviewcontroller {     private bool _constructed;      public mainview()     {             _constructed = true;              // need additional call viewdidload because uikit creates view before c# hierarchy has been constructed             viewdidload();     }      public override void viewdidload()     {         if (!_constructed)             return;          base.viewdidload();          var vm = (mainviewmodel)this.viewmodel;         if (vm == null)             return;     } }