根据 SwiftUI 日历中的值以不同颜色显示过去的日期

Question

我正在使用 SwiftUI 创建一个显示过去和当前日期的日历视图。我希望根据特定值以红色或绿色显示过去的日期。但是，我当前的实施仅适用于当天。谁能帮我修改代码，使其也适用于过去的日期？

这是 SimpleCalendar 视图的代码：

struct SimpleCalendar: View {
let startDate: Date
let endDate: Date
let content: (Date) -> Color
let items: FetchedResults<Item>

@State private var selectedMonth: Date
@Environment(\.calendar) var calendar

init(startDate: Date, endDate: Date, content: @escaping (Date) -> Color, items: FetchedResults<Item>) {
    self.startDate = startDate
    self.endDate = endDate
    self.content = content
    self.items = items
    _selectedMonth = State(initialValue: Calendar.current.date(from: Calendar.current.dateComponents([.year, .month], from: Date()))!)
}

func dailyValue(for date: Date) -> Int {
    let startOfDay = Calendar.current.startOfDay(for: date)
    let endOfDay = Calendar.current.date(byAdding: .day, value: 1, to: startOfDay)!
    
    let itemsForDay = items.filter { $0.timestamp! >= startOfDay && $0.timestamp! < endOfDay }
    let value = itemsForDay.reduce(0) { total, item in
        total + (item.isGood ? 1 : -1)
    }
    
    return value
}

func colorForDate(_ date: Date) -> Color {
    if hasEntry(for: date) {
        let value = dailyValue(for: date)
        return value >= 0 ? Color.green : Color.red
    } else {
        return Color.gray
    }
}

var body: some View {
    VStack {
        Picker("Select Month and Year", selection: $selectedMonth) {
            ForEach(availableMonthsAndYears(), id: \.1) { monthAndYear, date in
                Text(monthAndYear).tag(date)
            }
        }
        .pickerStyle(MenuPickerStyle())
        .padding()

        HStack {
            ForEach(months, id: \.self) { month in
                VStack {
                    CalendarMonthGrid(startDate: startDate, endDate: endDate) { date in
                        Group{
                            let value = dailyValue(for: date)
                            ZStack {
                                content(date)
                                    .frame(width: 25, height: 25)
                                    .cornerRadius(5)
                                Text("\(calendar.component(.day, from: date))")
                                    .foregroundColor(value != 0 ? .black : .white)
                            }
                        }
                    }
                }
            }.padding()
    }
}

}

我试过修改 colorForDate 函数，但它似乎对过去的日期不起作用。任何帮助，将不胜感激。谢谢！

这是我的 CoreData 实体的样子：