Fetch recurring objects using CoreData predicate

Hello!

I was wondering if there's any open source example how to implement SUBQUERY in CoreData in calendar based app? For example:

1. User creates an event with subtasks on the 1st on September with daily frequency
2. On the 5th of September they update just that day event's details, some subtasks.
3. On the 7th of September they see the same event that was created on the 1st of September.

Structs that can describe the case may look like this:

enum Frequency {
    case daily
    case weekly
    case monthly
}

struct Subtask {
    var name: String
    var isCompleted: Bool
}

struct Event {
    var id: UUID
    var name: String
    var startAt: Date
    var repeatUntil: Date?
    var isCompleted: Bool
    var subtasks: [Subtask]
    var frequency: Frequency?
    var excludedOn: [Date]
}

For each day on a week I need to fetch events from CoreData, so I'm wondering how predicate can look like in such case?

I met SUBQUERY, but I'm not sure how to apply weekly and monthly frequency frequency into NSPredicate (for daily it's pretty straightforward).

Would be glad for any advices!

~Paul