Core Data, Nested List

Question

I'm try to use my data that fetched from Core Data in nested list, but when I add the "children: .listofTasksArray" the following error is shown: "Key path value type '[ListOfTasks]?' cannot be converted to contextual type 'FetchedResults?'" this is the core data file

extension ListOfTasks {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<ListOfTasks> {
        return NSFetchRequest<ListOfTasks>(entityName: "ListOfTasks")
    }

    @NSManaged public var addedDate: Date?
    @NSManaged public var color: String?
    @NSManaged public var favoriteIndex: Int16
    @NSManaged public var icon: String?
    @NSManaged public var id: UUID?
    @NSManaged public var index: Int16
    @NSManaged public var isArchived: Bool
    @NSManaged public var isFavorite: Bool
    @NSManaged public var isLocked: Bool
    @NSManaged public var title: String?
    @NSManaged public var isList: Bool
    @NSManaged public var origin: ListOfTasks?
    @NSManaged public var subLists: NSSet?
    
    // The wrapped items
    public var wrappedAddedDate: Date {
        return addedDate ?? Date()
    }

    // To convert the color from "String" to "Color" type
    public var wrappedColor: Color {
        return Color(colorName: color ?? "blue")
    }
    
    public var wrappedIcon: String {
        return icon ?? "ellipsis.circle.fill"
    }
    
    public var wrappedId: UUID {
        return id ?? UUID()
    }
    
    public var wrappedTitle: String {
        return title ?? "Unknown Title"
    }
    
    public var listofTasksArray: [ListOfTasks]? {
        let set = subLists as? Set<ListOfTasks> ?? nil
        
        return set?.sorted { // sort by index
            $0.index > $1.index
        }
    }
}

and this is the list code that I used to fetch the data and use it in the list trying to make nested list using ListOfTasks property "listofTasksArray" as a child for the list.

struct ListsView: View {

    @FetchRequest(entity: ListOfTasks.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \ListOfTasks.index, ascending: true)], animation: .default) private var lists: FetchedResults<ListOfTasks>

var body: some View {

    List(lists, children: \.listofTasksArray, rowContent: { Text($0.wrappedTitle) })

}
}

Asperi · Accepted Answer · 2021-01-21 05:07:40Z

1

Types of data container are expected to be the same, so try to wrap FetchedResults into an array, like (might be some tuning needed do to optionals)

var body: some View {
    List(Array(lists), children: \.listofTasksArray) { 
       Text($0.wrappedTitle
    }
}

answered Jan 21, 2021 at 5:07

Asperi

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1 Comment

Ammar Ahmad Over a year ago

Thank you, its work know, did there is any way to convert the "FetchedResults" to an "Array" So I can deal with it as regular array in "SwiftUI"

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