CODEWITHSUNDEEP
iosswiftfunctional-programming
gmoraleda
gmoraleda

Reputation: 1953

Swift: Filter nested arrays

I'm trying to filter an array of Deals with a status DealStaus which has a nested array of Bookings, each one with a BookingStatus. I want to filter Deals with status .won and Bookings according to the statuses given when calling the function. BookingStatus and DealStatus are both enums. Deal and Booking look like this:

public struct Deal: Decodable {
    public let identifier: String?
    public let status: DealStatus
    public let bookings: [Booking]?
}

public struct Booking: Decodable {
    public let identifier: String?
    public let status: BookingStatus
    public let startDate: Date?
    public let endDate: Date?
}

To do so I wrote the following snippet:

private func getDeals(with bookingStatus: [BookingStatus]) -> [Deal] {
    guard let user = currentUser, let deals = user.deals else { return [Deal]() } // Note: user is a class attribute

    return deals.filter { $0.status == .won && $0.bookings?.filter { bookingStatus.contains($0.status) }}

}

This does not work. The compiler gives the following error:

Optional type '[Booking]?' cannot be used as a boolean; test for '!= nil' instead

Upvotes: 0

Views: 1781

Answers (1)

gmoraleda
gmoraleda

Reputation: 1953

Following the instructions of @matt, I broke it down:

private func getDeals(with bookingStatus: [BookingStatus]) -> [Deal] {
    guard let user = currentUser, let deals = user.deals else { return [Deal]() }
        return deals
            .filter { $0.status == .won }
            .filter { $0.bookings?.contains(where: { bookingStatus.contains($0.status)} ) ?? false }
    }

Upvotes: 5

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