如何顯示已過濾對象數組的計數

Question

我有一個對象數組，代表幾個部分。 每個部分包含許多項目。 我設法過濾所有部分以在UITableView顯示所需的項目，但是我無法從我的部分中獲得正確的項目數。 每次過濾數組后，我都會得到原始的項目計數。 我的控制台說： Number of items in each section: [9, 6] UITableView Number of items in each section: [9, 6]但實際上我的UITableView中只有[ UITableView ]。 如何反映適量的項目以繼續使用數組？ 這是我的代碼：

// MARK : MODEL
class ChecklistItemSection{

    var name: String // name of the section
    var checklistItems: [ChecklistItem] // all items from Checklist

    init(named: String, checklistItems: [ChecklistItem]) {

        self.name = named
        self.checklistItems = checklistItems
    }

    class func checklistItemSections() -> [ChecklistItemSection] {

        var allSections = [vehicleCheck(), viewingScreen(), batteryUnitAndFridge()]

        for (index, section) in allSections.enumerated() {
            if(section.checklistItems.count < 1) {
                allSections.remove(at: index)
            }
        }
        return allSections
    }

    // Private methods
    private class func vehicleCheck() -> ChecklistItemSection {

        var checklistItems = [ChecklistItem]()

        checklistItems.append(ChecklistItem(templateID: 109, lineID: 3, poolID: 10, descript: "Tyres - Wear/Damage/Bulges/Cuts/Flat tyres", showVehicle: false, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 4, poolID: 22, descript: "Vehicle and trailer coupling: undamaged and safety locking device working", showVehicle: true, showTrailer: false, highlight: true, pg9: true, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 7, poolID: 20, descript: "Exhaust - Condition/Emission (Excess smoke)", showVehicle: true, showTrailer: false, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 3, poolID: 10, descript: "Tyres - Wear/Damage/Bulges/Cuts/Flat tyres", showVehicle: true, showTrailer: false, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 4, poolID: 22, descript: "Vehicle and trailer coupling: undamaged and safety locking device working", showVehicle: true, showTrailer: true, highlight: true, pg9: true, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 7, poolID: 20, descript: "Exhaust - Condition/Emission (Excess smoke)", showVehicle: false, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 3, poolID: 10, descript: "Tyres - Wear/Damage/Bulges/Cuts/Flat tyres", showVehicle: false, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 4, poolID: 22, descript: "Vehicle and trailer coupling: undamaged and safety locking device working", showVehicle: true, showTrailer: true, highlight: true, pg9: true, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 109, lineID: 7, poolID: 20, descript: "Exhaust - Condition/Emission (Excess smoke)", showVehicle: false, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)

        return ChecklistItemSection(named: "Section 1", checklistItems: checklistItems)
    }

    private class func viewingScreen() -> ChecklistItemSection {

        var checklistItems = [ChecklistItem]()

        checklistItems.append(ChecklistItem(templateID: 38, lineID: 28, poolID: 16, descript: "Windscreen Wipers & Washers are they effective?", showVehicle: true, showTrailer: false, highlight: false, pg9: false, imagesPath: [])!)

        checklistItems.append(ChecklistItem(templateID: 38, lineID: 28, poolID: 16, descript: "Water Level - In cab indicator", showVehicle: true, showTrailer: false, highlight: false, pg9: false, imagesPath: [])!)

        return ChecklistItemSection(named: "Section 2", checklistItems: checklistItems)
    }

    private class func batteryUnitAndFridge() -> ChecklistItemSection {

        var checklistItems = [ChecklistItem]()

        checklistItems.append(ChecklistItem(templateID: 38, lineID: 31, poolID: 38, descript: "Battery is held securely in place by the correct means (not cables)", showVehicle: true, showTrailer: true, highlight: false, pg9: true, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 38, lineID: 32, poolID: 39, descript: "Battery cables and pins secure", showVehicle: true, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 38, lineID: 33, poolID: 40, descript: "Battery is not leaking", showVehicle: true, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 38, lineID: 34, poolID: 38, descript: "Battery is held securely in place by the correct means (not cables)", showVehicle: true, showTrailer: true, highlight: false, pg9: true, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 38, lineID: 35, poolID: 39, descript: "Battery cables and pins secure", showVehicle: false, showTrailer: true, highlight: false, pg9: false, imagesPath: [])!)
        checklistItems.append(ChecklistItem(templateID: 38, lineID: 35, poolID: 39, descript: "Battery is not leaking", showVehicle: true, showTrailer: false, highlight: false, pg9: false, imagesPath: [])!)

        return ChecklistItemSection(named: "Section 3", checklistItems: checklistItems)
    }
}

class ChecklistItem {

    var showVehicle: Bool
    var showTrailer: Bool
}

// MARK: VC

class ChecklistVC: UIViewController {

    lazy var checklistItem: [ChecklistItemSection] = { return ChecklistItemSection.checklistItemSections() }()

    override func viewDidLoad() {
        super.viewDidLoad()

        filterQuestions()
    }

    func filterQuestions() {

        // Show only the questions available for Trailer
        if vehicleRegistrationNumber.isBlank {

            checklistItem.forEach {
                $0.checklistItems.forEach {
                    if $0.showVehicle {
                        $0.showVehicle = false
                    }
                }
            }

            checklistItem = checklistItem.filter { $0.checklistItems.filter { $0.showTrailer && !$0.showVehicle }.count != 0 }.filter {$0.checklistItems.count > 0}
        }

        print("Number of items in each section: \(checklistItem.map {$0.checklistItems.count})") // I get [9, 6] every time. But it should display [6, 5] reflecting the items after filtering.
    }
}

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Answer 1

如您所知， filter實際上並未刪除項目。 它只是返回一個刪除了某些項目的新數組。 因此，當您執行以下嵌套過濾器時：

checklistItem.filter { $0.checklistItems.filter { ... }.count != 0 }

它將返回checklistItem但刪除了一些元素，然后將此結果分配給checklistItem ，從而對其進行更改。 但是請注意， checklistItem的內部數組（即checkListItems ）沒有更改！

內部filter只返回一個新數組（並且實際上不修改數組本身）。

我建議你forEach的事情checklistItem ， removeAll滿足標准，則刪除所有的checklistItems是使用另一種空removeAll ：

checklistItem.forEach { $0.checklistItems.removeAll { !$0.showTrailer || $0.showVehicle } }
checklistItem.removeAll { $0.count == 0 }

最后，您不需要額外的過濾器。