SwiftUI crashes preview when pass parameters to the view

Question

import SwiftUI
import CoreData

struct CategoryOverview: View {
    var category: Category
    
    var body: some View {
        VStack(alignment: .leading) {
            HStack {
                Text(category.name ?? "")
                    .font(.title)
                Spacer()
            }
            Text(String(category.records?.count ?? 0))
                .font(.subheadline)
        }
        .padding()
        .foregroundColor(Color.white)
        .background(Color.blue)
        .clipShape(RoundedRectangle(cornerRadius: 10))
    }
}

struct CategoryOverview_Previews: PreviewProvider {
    static var previews: some View {
        let category = Category()
        category.id = UUID()
        category.timestamp = Date()
        category.name = "Clean"

        return CategoryOverview(category: category)
    }
}

I defined Category entity in Core Data model. Then I built a simple view to show the name of a category. I tried to pass a Category instance to the preview struct, but preview crashed always. There is no detail logs for this crash. It just said "the preview process appears to have crashed".

This view works well in other views such as main ContentView . So, the code is fine, but I suspect that my preview code is wrong.

I'm very new to Swift and Swift UI. Did I miss something?

Answer 1

Since Category is a Core Data model you need a context

change

let category = Category()

To something like

let category = Category(context: PersistentController.preview.container.viewContext)

If you use the standard setup. If not just fill in the context variable whichever way you traditionally use it.