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标题: ios - 在表格 View 单元格中使用步进器 - 但返回 VC 的数据未正确更新 [打印本页]

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作者: 菜鸟教程小白    时间: 2022-12-11 17:52
标题: ios - 在表格 View 单元格中使用步进器 - 但返回 VC 的数据未正确更新

我正在尝试创建一个配置屏幕，以便用户可以设置他或她想要进行的锻炼次数。我设法将一个表格 View 添加到一个空白 View Controller ，但存在一些风格限制 - 例如根据单元格的数量展开和折叠表格 View 。

所以我想我会在 tableviewcontroller 中设置屏幕。现在一切顺利，直到我希望 section 0、cell 1 中的 Stepper 增加和减少section 1 中的行数。它的工作原理是数据数组(workouts[])用最新的值(在 cellForRowAt:indexPath 方法中)更新 View Controller ，这反过来又更新了 numberOfRowsInSection使用(据说)最新的 workouts.count。

然而，事实证明 workouts.count 在步进器最后更新数组之前保存了计数。

现在，我尝试了多种解决方法，但仍然无法正确更新 numberOfRowsInSection 方法 - 在我看来，View Controller 中的 Workouts 数组没有更新为最新的值，而不是之前的设定值。

这是我的 View Controller :

class AViewController: UITableViewController {

//MARK: Properties
@IBOutlet weak var aTableView: UITableView!

var sections: [String] = ["", "Set Up Circuits"]
var workouts: [Exercise] = []

//MARK: Initialisation
override func viewDidLoad() {
    super.viewDidLoad()
    workouts = [Exercise(name: "Circuit 1", timeMinutes: 2)]
    self.tableView.delegate = self
    self.tableView.dataSource = self
}

//MARK: Table Config
override func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    return self.sections[section]
}

override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    switch section {
    case 0:
        return 0.1
    default:
        return 32.0
    }
}

override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    switch indexPath.section {
    case 0:
        return 60
    default:
        return 44
    }
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    var numberOfRowsInSection: Int = 0

    switch section {
    case 0:
        numberOfRowsInSection = 1
    default:
        numberOfRowsInSection = workouts.count
        //numberOfRowsInSection = 1
    }
    print(numberOfRowsInSection, "number of rows in section", section)
    return numberOfRowsInSection
}

//MARK: Table Protocols
override func numberOfSections(in tableView: UITableView) -> Int {
    return sections.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    switch indexPath.section {

    //Setting layout for circuit number config
    case 0:
        let cell = aTableView.dequeueReusableCell(withIdentifier: "ACircuitTableViewCell") as! ACircuitTableViewCell
        cell.tableView = self.aTableView
        self.workouts = cell.workouts
        print(workouts.count, " VC workouts array count")
        return cell

    //Setting layout for circuit cells
    default:
        let cell = aTableView.dequeueReusableCell(withIdentifier: "ATableViewCell") as! ATableViewCell
        cell.aLabel.text = workouts[indexPath.row].getName()
        cell.aDetail.text = "Tap here to configure"
        return cell

    }
}

这是我的 ACircuitTableViewCell:

class ACircuitTableViewCell: UITableViewCell {

//MARK: Properties
@IBOutlet weak var circuitNumber: UILabel!
@IBOutlet weak var circuitLabel: UILabel!
@IBOutlet weak var circStepper: UIStepper!


var tableView: UITableView!
// var updateCallback : ((_ updateList: Bool)-> Void)?

//var exercises: [Exercise]?
var anArray: [Exercise] = []
var workouts: [Exercise] = [Exercise(name: "Circuit 1", timeMinutes: 2)]

var workoutsCount: Int = 1
var indexPath: NSIndexPath = NSIndexPath(row: 0, section: 1)
//MARK: Original Functions
override func awakeFromNib() {
    super.awakeFromNib()
    // Initialization code

    circuitNumber.text = String(workouts.count)
}

override func setSelected(_ selected: Bool, animated: Bool) {
    super.setSelected(selected, animated: animated)
}

@IBAction func valueChanged(_ sender: AnyObject) {
    print("Method .valueChanged activated")

    //Update circuitNumber label
    circuitNumber.text = String(Int(circStepper.value))

    //View pre-array-update status of variables
    print(workouts.count, "anArray before appending")
    print(circStepper.value, "stepper value before appending")
    print(circuitNumber.text, "circuitNumber")

    //Update workouts array
    if workouts.count < Int(circStepper.value) {
        workouts.append(Exercise(name: "Circuit \(Int(circStepper.value))", timeMinutes: 2))
        print(workouts.count, "after appending")

        tableView.reloadData()

       print(workouts.count, "new workout.count")
    }


    print(workouts.count, "workouts.count")
    print("Method .valueChanged completed")

}

这是从应用加载到点击步进器 + 按钮三下到控制台的输出。

1 number of rows in section 1
1 number of rows in section 0
1 number of rows in section 1
1 number of rows in section 0
1 number of rows in section 1
1 number of rows in section 0
1  VC workouts array count
Method .valueChanged activated
1 anArray before appending
2.0 stepper value before appending
Optional("2") circuitNumber
2 after appending
1 number of rows in section 1
1 number of rows in section 0
2 new workout.count
2 workouts.count
Method .valueChanged completed
2  VC workouts array count
Method .valueChanged activated
2 anArray before appending
3.0 stepper value before appending
Optional("3") circuitNumber
3 after appending
2 number of rows in section 1
1 number of rows in section 0
3 new workout.count
3 workouts.count
Method .valueChanged completed
3  VC workouts array count
Method .valueChanged activated
3 anArray before appending
4.0 stepper value before appending
Optional("4") circuitNumber
4 after appending
3 number of rows in section 1
1 number of rows in section 0
4 new workout.count
4 workouts.count
Method .valueChanged completed
4  VC workouts array count
Method .valueChanged activated
4 anArray before appending
5.0 stepper value before appending
Optional("5") circuitNumber
5 after appending
4 number of rows in section 1
1 number of rows in section 0
5 new workout.count
5 workouts.count
Method .valueChanged completed
5  VC workouts array count

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Best Answer-推荐答案

您应该在 Controller 中处理步进回调并在那里更改 viewController 的数据源。

1. 在 View Controller 中处理单元格事件的最常见方法是使用委托(delegate)，就像我在这里描述的那样: https://stackoverflow.com/a/40111943/1689376

2. 或者，您可以在 cellForRow 方法中添加带有 self 目标的操作:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell") as! TableViewCell
    cell.stepper?.tag = indexPath.row
    cell.stepper?.addTarget(self, action: #selector(stepperValueChanged(_), for: .valueChanged)
    return cell
}

func stepperValueChanged(_ stepper: UIStepper) {
    //use stepper.tag as index to fetch an object from your dataSource
    let workout = dataSource[stepper.tag]
}

关于ios - 在表格 View 单元格中使用步进器 - 但返回 VC 的数据未正确更新，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/40105491/

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