ios - 如何通过页脚单元格在表格 View 中使用委托(delegate)？

Question

我试图做的是通过 CalorieFooter 单元格中的按钮将数据传递给另一个 View Controller ，使用委托(delegate)在单元格中传递数据。

我无法通过 中的 infoButton 成功传递数据卡路里页脚 单元格以在 CalorieBreakdownController 中显示当天卡路里消耗的脂肪、碳水化合物和蛋白质。

我目前在 CalorieBreakdownController 的所有标签中都得到“0”(如图像最右侧所示)。

我认为问题可能是因为我的 计算委托(delegate) 在 CalorieFooter 单元格中完成。我在单元格中获得小计的方法是将单元格分成几个部分。我对如何从页脚将数据传递给 CalorieBreakdownController 以获取标签中的“小计”有点困惑。

我如何能够从 calorieFooter 单元格中将“subTotal”数据传递给 CalorieBreakdownController(如下图所示)

提前感谢您提供的任何帮助

 import UIKit

 class CalorieViewController: UIViewController {

    var selectedFood: FoodList!
    var additionalCalories: DailyCalories!                  // delegate code for footer

    var calorieItems: [DailyCalories] = []
    var groupedCalorieItems: [String: [DailyCalories]] = [:]
    var dateSectionTitle: [DailyCalories] = []

    @IBOutlet weak var calorieTableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()

        groupedFoodItems = Dictionary(grouping: calorieItems, by: {$0.foodList.day})
        dateSectionTitle = groupedCalorieItems.map{$0.key}.sorted()

    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
         if let vc = segue.destination as? CalorieTotalController {   // delegate code for footer
            vc.additionalCalories = self.additionalCalories
        }
    }
}

extension CalorieViewController: UITableViewDelegate, UITableViewDataSource {

    func numberOfSections(in tableView: UITableView) -> Int {
        return dateSectionTitle.count
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        let date = dateSectionTitle[section]
        return groupedCalorieItems[date]!.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let calorieCell = tableView.dequeueReusableCell(withIdentifier: "CalorieCell") as! CalorieCell

        let date = dateSectionTitle[indexPath.section]
        let calorieItemsToDisplay = groupedCalorieItems[date]![indexPath.row]
        calorieCell.configure(withCartItems: calorieItemsToDisplay.foodList)

        return calorieCell
    }

    func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
        let calorieHeader = tableView.dequeueReusableCell(withIdentifier: "CalorieHeader") as! CalorieHeader

        let headerTitle = dateSectionTitle[section]
        calorieHeader.dateLbl.text = "Date: \(headerTitle)"

        return calorieHeader
    }

    func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
        let calorieFooter = tableView.dequeueReusableCell(withIdentifier: "CalorieFooter") as! CalorieFooter

        let date = dateSectionTitle[section]
        let arrAllItems = groupedCalorieItems[dispensary]!
        var subtotal: Float = 0
        for item in arrAllItems {
            if item.foodList.selectedOption == 1 {
                 subtotal = subtotal + (Float(item.foodList.calorie1) * Float(item.foodList.count))
            } else if item.foodList.selectedOption == 2 {
                 subtotal = subtotal + (Float(item.foodList.calorie2) * Float(item.foodList.count))
            } else if item.foodList.selectedOption == 3 {
                 subtotal = subtotal + (Float(item.foodList.calorie3) * Float(item.foodList.count))
            }
        }

        calorieFooter.cartTotal.text = "\(subtotal)"
        calorieFooter.calculationDelegate = self                  // delegate code for footer
        calorieFooter.additionalCalories! = ???                   // can't get the right code set to allow the data to pass
        calorieFooter.calculations! = ???                         // can't get the right code set to allow the data to pass
        return calorieFooter
    }  
}

extension CalorieViewController: CalculationDelegate {     // delegate code for footer
    func onTouchInfoButton(from cell: CalorieFooter) {
        self.additionalCalories = cell.additionalCalories
        self.performSegue(withIdentifier: "CalculateDailyCalorieCell", sender: self)
    }
}

import UIKit

protocol CalculationDelegate: class {                     // delegate code for footer
    func onTouchInfoButton(from cell: CalorieFooter)
}

class CalorieFooter: UITableViewCell {

    weak var calculationDelegate: CalculationDelegate?   // delegate code for footer
    var additionalCalories: DailyCalories!                            // delegate code for footer
    var calculations: [DailyCalories] = []

    @IBOutlet weak var calorieTotal: UILabel!

    @IBOutlet weak var additionalFeesBtn: UIButton!


    @IBAction func overallTotalBtn(_ sender: Any) {
         self.additionalFeesDelegate?.onTouchInfoButton(from: self)   // delegate code for footer
    }
}

class CalorieTotalController: UIViewController {

    var additionalCalories: DailyCalories!             // delegate code for footer
    var calculations: [DailyCalories] = []            // delegate code for footer

    @IBOutlet weak var calorieSubtotal: UILabel!

    @IBOutlet weak var fatTotal: UILabel!
    @IBOutlet weak var carbTotal: UILabel!
    @IBOutlet weak var proteinTotal: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        // calculations done for when data is passed through Delegate
        var subtotal: Float = 0
        for item in calculations {
            if item.foodList.selectedOption == 1 {
                 subtotal = subtotal + (Float(item.foodList.calorie1) * Float(item.foodList.count))
            } else if item.foodList.selectedOption == 2 {
                 subtotal = subtotal + (Float(item.productList.calorie2) * Float(item.foodList.count))
            } else if item.foodList.selectedOption == 3 {
                 subtotal = subtotal + (Float(item.foodList.calorie3) * Float(item.foodList.count))
            }
        }

        let protein = Float(subtotal * 0.25)
        let carbs = Float(subtotal * 0.25)
        let fat = Float(subtotal * 0.5)

        calorieSubtotal.text = String(subtotal!)
        proteinTotal.text = String(protein!)
        fatTotal.text = String(fat!)
        carbTotal.text = String(carbs!)

    }

    @IBAction func closeButton(_ sender: Any) {
        dismiss(animated: true, completion: nil)
        print("Calories BreakDown")
    }    
}

Answer 1

使用委托(delegate)可能是一个好主意。我只是写了一些代码(未经测试!)让您了解它是如何工作的:

扩展委托(delegate)类:

protocol CalculationDelegate: class {
    func onTouchInfoButton(from cell: CalorieFooter)
    func getAdditionalCalories() -> Int
    func getCalculations() -> Int // or whatever type this object should be
}

确保您的 View Controller 遵循协议(protocol):

extension CalorieViewController: CalculationDelegate { 
    func onTouchInfoButton(from cell: CalorieFooter) { ... }
    func getAdditionalCalories() -> Int {
        return self.calories
    }
    func getCalculations() -> Int {
        return self.calculations
    }
}

将局部变量添加到 CalorieViewController存储当前状态(卡路里/计算量)

class CalorieViewController: UIViewController {
    private var calories: Int = 0
    private var calculations: Int = 0

    ... other code that is already in the UIViewController
}

确保在某处初始化这些变量!就像是:

func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? {
    ... same as before...

    self.calories = subtotal // I guess?
    self.calculations = calculations // put this somewhere where calculations is initialized
}

现在，数据应该在 CalorieFooter 中可用。 .当calculationDelegate为 nil时，我添加了默认值0 :

let calories = calculationDelegate?.getAdditionalCalories() ?? 0
let calculations = calculationDelegate?.getCalculations() ?? 0

祝你好运!