How to use Core Data with Swift Charts?

Question

I'm doing FetchRequest

@Environment(\.managedObjectContext) var managedObjContext
        @FetchRequest(sortDescriptors: [SortDescriptor(\.date, order: .reverse)]) 
var day: FetchedResults<Item>

And then I put it in Charts, but Swift Charts need Plottable, and it seems to me that there is no way to convert it.

Help, please!

Trying to do this kind of thing, but it doesn't work. Mistake: Cannot convert value of type '() -> BarMark' to expected argument type '(FetchedResults.Element) -> BarMark' (aka '(Item) -> BarMark'). I should convert my core data to Plottable, I think, ad I don't no how.

import SwiftUI
import Charts

struct ChartView: View {
    
    @Environment(\.managedObjectContext) var managedObjContext
    @FetchRequest(sortDescriptors: [SortDescriptor(\.date, order: .reverse)]) var day: FetchedResults<Item>
    @State var low = 0
    @State var top = 0
    @State var ir = 0
    @State var date = Date()
    
    var body: some View {
        
        Chart(day) {
            BarMark(
                x: .value("Day", low),
                y: .value("Sales", top)
            )
                
            }
        }
        
    }

Remove the $. Binding is for when you need a two way connection — lorem ipsum, Dec 28 '22 at 10:32
It gives a mistake: Cannot convert value of type '() -> BarMark' to expected argument type '(FetchedResults.Element) -> BarMark' (aka '(Item) -> BarMark') — Daniil Artemenko, Dec 28 '22 at 11:00

score 0 · Answer 1 · answered Dec 30 '22 at 17:07

I've found pretty easy solution, code:

struct ChartView: View {

@Environment(\.managedObjectContext) var managedObjContext
@FetchRequest(sortDescriptors: [SortDescriptor(\.date, order: .reverse)]) var items: FetchedResults<Item>
@State var low = 0
@State var top = 0
@State var ir = 0

func getDate(date: Date)->String {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "MMM dd"
    let stringDate = dateFormatter.string(from: date)
    return stringDate
}


var body: some View {
    Chart {
        ForEach(items.prefix(5)) { item in
            var dateInitial = getDate(date:(item.date!))
            LineMark(x: .value("date", "\(item.date)"), y: .value("hours slept", item.top))
                .cornerRadius(8.0)
                .annotation(position: .overlay, alignment: .top, spacing: 2.0) {
                    Text("\(item.top, specifier: "%.2f")")
                        .font(.system(size:10))
                        .foregroundColor(.white)
                        .fontWeight(.bold)
                }
        }
        
        
    }
}
}



struct ChartView_Previews: PreviewProvider {
static var previews: some View {
    ChartView()
}
}

How to use Core Data with Swift Charts?

1 Answers1