CODEWITHSUNDEEP
swiftuiobservableobject
MrRog
MrRog

Reputation: 31

Changes not propagating to SwiftUI View

I have trouble understanding why certain changes in my data do not propagate to my SwiftUI View.

This is a very minimal set-up to illustrate the issue:

public class Model: ObservableObject
{
   @Published var anArray: [String]

   // Calling this does NOT update the View
   func addItem(item: String) {
      anArray.append(item)
   }
}

public class ViewModel: ObservableObject
{
   @Published var model: Model

   // Calling this updates the View
   func addItem(item: String) {
      model.addItem(item)
   }

   func getItem(index: Int) {
      return model.anArray[index]
   }
}

struct aView: View {
    @ObservedObject var viewModel: ViewModel
    
    var body: some View {
        VStack {
            Text(viewModel.getItem(index: 0))
        }
    }
}

So when I use the addItem() function on the ViewModel, my View gets updated. But in any situation where anArray in the same instance of the model class gets updated outside of the ViewModel, the View does not update. I would expect that the model property would also publish changes to the referenced object when they happen from outside the ViewModel. But obviously I misunderstand something.

How do I achieve updating the View based on model updates that happen through modifications outside of ViewModel's context?

Upvotes: 0

Views: 21

Answers (0)

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