swiftui @State value depends on @ObservedObject ViewModel init error

Question

I have simple viewModel:

final class EmployeeListViewModel: ObservableObject {
 @Published var list = [Employee]()
 init() {
  // some request
  self.list = [Employee, Employee]
 }
}

And have a view:

struct EmployeeView: View {
 @ObservedObject var viewModel = EmployeeListViewModel()
 @State private var showContents: [Bool] = Array(repeating: false, count: viewModel.list.count)// <- error throws here
 var body: some View {
        GeometryReader { fullView in
            ScrollView {
                VStack(spacing: 40) {
                  ForEach(self.viewModel.list) { employee in
                     Text(employee.firstName).foregroundColor(.black)
                  }
                }
            }
        }
 }
}

Error text:

Cannot use instance member 'viewModel' within property initializer; property initializers run before 'self' is available

I tried change it with init:

struct EmployeeView: View {
 @ObservedObject var viewModel = EmployeeListViewModel()
 @State private var showContents: [Bool]

 init() {
        _showContents = State(initialValue: Array(repeating: false, count: viewModel.list.count)) // <- error
    }

 var body: some View {
        GeometryReader { fullView in
            ScrollView {
                VStack(spacing: 40) {
                  ForEach(self.viewModel.list) { employee in
                     Text(employee.firstName).foregroundColor(.black)
                  }
                }
            }
        }
 }
}

But it also throws error:

'self' used before all stored properties are initialized

this throws on I call viewModel on init()

How to solve it? @State i use for card view. There I simplified views for easy understand.

Does this answer your question? [How to initialize properties that depend on each other](https://stackoverflow.com/questions/25854300/how-to-initialize-properties-that-depend-on-each-other). Or this, https://stackoverflow.com/questions/43550813/property-initializers-run-before-self-is-available — Joakim Danielson, Jul 09 '20 at 05:43
@JoakimDanielson I updated question. `init` doesnt resolve. Or I used it with mistake — aturan23, Jul 09 '20 at 05:50
@JoakimDanielson tried move code on `init` to `onAppear` it throws `Cannot assign to property: 'self' is immutable` — aturan23, Jul 09 '20 at 06:03

score 1 · Answer 1 · answered Jul 09 '20 at 06:13

First initialise the state variable to an empty array

@State private var showContents: [Bool] = []

then set it in the init

init() {
    showContents = Array(repeating: false, count: viewModel.list.count)
 }

You shouldn't initialise the view model property in the view but rather use dependency injection

init(viewModel: EmployeeListViewModel) {
    self.viewModel = viewModel
    showContents = Array(repeating: false, count: viewModel.list.count)
}

score 0 · Accepted Answer · answered Jul 09 '20 at 06:08

Here is possible solution

struct EmployeeView: View {
 @ObservedObject var viewModel: EmployeeListViewModel     // << declare
 @State private var showContents: [Bool]                  // << declare

 init() {
       let vm = EmployeeListViewModel()   // create here !!

       // initialize both below
       self.viewModel = vm                     
       self._showContents = State(initialValue: Array(repeating: false, 
              count: vm.list.count))
    }

swiftui @State value depends on @ObservedObject ViewModel init error

2 Answers2