CODEWITHSUNDEEP
xamarinxamarin.forms
dr11
dr11

Reputation: 5726

Getting control after INavigation.PopAsync() in Xamarin Forms

I have PageA + ViewModelA, and PageB + ViewModelB.

From A i'm calling PushAsync(B), editing some data, and calling PopAsync().

So now B becomes closed, and user returns to A.

But in B user changed some state, that should be update on A. What is the correct way to notify A to update state (and it would be better to have access to ViewModelB).

Approaches:

1. In B call PopAsync(), from NavigationStack get ViewModelA and manually trigger some update method
2. [doesn't work for me] In A call PushAsync(B) and wait until B becomes closed, so after that perform update with access to VMB (PushAsync doesn't lock A, so this approach doesn't work)

Seems both of these approaches are incorrect.

Upvotes: 0

Views: 250

Answers (1)

Depechie
Depechie

Reputation: 6142

Normally in a MVVM environment, when you need to 'signal' changes to other ViewModels, you use a Messaging system. Depending on the MVVM framework you'll need to look at what class is available for this.

In xamarin forms you'll have the messaging center https://developer.xamarin.com/guides/cross-platform/xamarin-forms/messaging-center/

Upvotes: 1

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