I'm using Unity and Prism EventAggregator in my MVVMC application I have a process which contains multiple steps, basically a wizard.
My controller resolves my outer View (call it WizardView)
and adds it to the main region.
WizardView contains
a breadcrumb trail to show the progress through the wizard and a sub Region to load other views into (call this WizardRegion). Step1View is
the first View loaded intoWizardRegion.
Each view has it's ViewModel injected into the constructor using the Unity container.
WizardViewModel subscribes
to several event aggregation events which are published by the step view models.
As each step is completed the View Model publishes an event which WizardViewModel uses
to store the state, this means WizardViewModel is
collecting the data from each step as we progress. The step ViewModel also calls the controller to load the next step into WizardRegion.
At the final step WizardViewModel saves
the result of the wizard and the MainRegion is
navigated back to some other screen.
The next time we enter the wizard, we create a new instance of all the Views and ViewModels but the event subscriptions from the previous wizard still exist.
I've confirmed that I'm using weak events by passing false to the Subscribe method but I suspect that because they're not garbage collected the event is sill being handled. How can I make my ViewModels activation aware? I'm sure I've seen a link somewhere but cant find it again now.
Thanks
Ben