Swift：過濾嵌套數組

Question

我正在嘗試過濾狀態為DealStaus的Deals數組，其中DealStaus具有嵌套的Bookings數組，每個都有一個BookingStatus 。 我想根據調用該函數時給出的狀態來過濾狀態為.won和Bookings的Deals。 BookingStatus和DealStatus都是枚舉。 Deal和Booking看起來像這樣：

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?
}

為此，我編寫了以下代碼段：

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) }}

}

這是行不通的。 編譯器給出以下錯誤：

可選類型“ [預訂]？” 不能用作布爾值； 測試'！= nil'代替

Answer 1

按照@matt的說明，我將其分解為：

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 }
    }