SwiftUI - Static method 'buildExpression' requires that 'ValueWidget' conform to 'AccessibilityRotorContent'

Question

I am new to swift und swiftUI and started playing around with it. I am getting the following error:

Static method 'buildExpression' requires that 'ValueWidget' conform to 'AccessibilityRotorContent'. Screenshot from the error

ContentView.swift

struct ContentView: View {
    var body: some View {
        
        let data = (1...100).map { "Item \($0)" }

        let columns = [
            GridItem(.adaptive(minimum: 80))
        ]
        
        let v: Double = -10.0

        ScrollView {
                   LazyVGrid(columns: columns, spacing: 20) {
                       ForEach(data, id: \.self) { item in
                           ValueWidget(name: item, value: v)
                           v = v + 0.5;
                       }
                   }
                   .padding(.horizontal)
               }
               .frame(maxHeight: 300)
    }
}

/*
#Preview {
    ContentView()
}*/
struct ValueWidget_Previews: PreviewProvider {
    static var previews: some View {
        ValueWidget(name: "Hello", value: 42.0)
    }
}

ValueWidget.swift

import SwiftUI

struct ValueWidget: View {
    var name: String
    var value: Double
    
    var body: some View {
        VStack {
            Text(String(format: "%.1f", value))
                .font(.system(size: 40))
                .fontWeight(.bold)
            .foregroundColor(Color.blue)
            Text(name)
        }
        .padding()
        .background()
        .cornerRadius(10)
        .fixedSize()
        .frame(width: 120.0, height: 70.0)
        .padding()
        .accessibilityLabel(Text("\(name), Wert: \(value)"))
    }
}

#Preview {
    ValueWidget(name: "Hello", value: 42.0)
}

I have tried replacing

#Preview {
    ContentView()
}

with

struct ValueWidget_Previews: PreviewProvider {
    static var previews: some View {
        ValueWidget(name: "Hello", value: 42.0)
    }
}

as some research suggested. But this doesn't help.

I am using macOS Sonoma and Xcode 15.0

What is the best way to fix this problem?

Thank you very much

Answer 1

The explanation for why v = v + 0.5 must be omitted is that you cannot perform calculations within a View. These calculations should be factored out and into another file.