How to bind properties of a @State variable in a ForEach?

Question

class Form {
    var id = UUID()
    var name: String = ""
    var fields: [FormField] = []
}

class FormField {
    var id = UUID()
    var name: String = ""
}

struct LogCustomizationView: View {

    @State var form: Form

    var body: some View {
        VStack {
            ForEach(form.fields.indices) { idx in
                TextField("Name", text: self.$form.fields[dynamicMember: idx])
            }
        }
    }
}

The problematic line is:

TextField("Name", text: self.$form.fields[dynamicMember: idx])

The first error I got was

Missing argument label 'dynamicMember:' in subscript

So I added dynamicMember:, which is how it's shown above. Now the error I get is: Cannot convert value of type 'Int' to expected argument type 'WritableKeyPath<_, _>'

nine stones · Accepted Answer · 2020-02-01 02:51:36Z

1

SwiftUI errors can be really nebulous.

You are effectively trying to bind a FormField object to a Binding<String> where neither the object adopts BindableObject nor the name ivar (which you assumably want to bind) has a publisher attached to it (@Published).

I guess you want to bind the name ivar to the TextField:

  ForEach(form.fields.indices) { idx in
    TextField("Name", text: self.$form.fields[idx].name)
  }

answered Feb 1, 2020 at 2:51

nine stones

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1 Comment

Alex Over a year ago

Thank you! I'm just starting with SwiftUI had no idea about publishers- your helpful explanation is appreciated.

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