如何将步进值传递给ViewController？

如何解决如何将步进值传递给ViewController？

我有一个具有2个标签的自定义单元格，myLabel和numLabel，以及一个步进器。我的Swift档案和XIB档案中都有我的自订储存格。我想在步进器上单击+或-按钮时，numLabel随步进器的值而变化。我不知道如何将步进值传递给我的tableView所在的viewController。以后想将步进值保存到CoreDate中，该怎么办？我只是一个初学者。谢谢您的帮助。

MyCell.swift

import UIKit

class MyCell: UITableViewCell {
    
    static let identifier = "MyCell"
    
    static func nib() -> UINib {
        return UINib(nibName: "MyCell",bundle: nil)
    }
    
    public func configure(with name: String,number: String) {
        myLabel.text = name
        numLabel.text = number
    }
    
    @IBOutlet var myLabel: UILabel!
    @IBOutlet var numLabel: UILabel!
        
    

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

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

        // Configure the view for the selected state
    }
    
}

ViewController.swift

import UIKit

class ViewController: UIViewController,UITableViewDelegate,UITableViewDataSource {
    
    @IBOutlet var table: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()
        table.register(MyCell.nib(),forCellReuseIdentifier: MyCell.identifier)
        table.delegate = self
        table.dataSource = self
    }
    
    func tableView(_ tableView: UITableView,numberOfRowsInSection section: Int) -> Int {
        return 10
    }
    
    func tableView(_ tableView: UITableView,cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.identifier,for: indexPath) as! MyCell
        cell.configure(with: "Item 1",number: "1")
        return cell
    }


}

My Screen Shot

解决方法

您可以通过“回调”关闭轻松完成此操作：

class MyCell: UITableViewCell {
    static let identifier: String = "MyCell"
    
    @IBOutlet var myStepper: UIStepper!
    @IBOutlet var numLabel: UILabel!
    @IBOutlet var myLabel: UILabel!

    // "callback" closure - set my controller in cellForRowAt
    var callback: ((Int) -> ())?
    
    public func configure(with name: String,number: String) {
        myLabel.text = name
        numLabel.text = number
    }

    @IBAction func stepperChanged(_ sender: UIStepper) {
        let val = Int(sender.value)
        numLabel.text = "\(val)"
        // send value back to controller via closure
        callback?(val)
    }

    static func nib() -> UINib {
        return UINib(nibName: "MyCell",bundle: nil)
    }

}

然后，在cellForRowAt中：

override func tableView(_ tableView: UITableView,cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.identifier,for: indexPath) as! MyCell
    cell.configure(with: "Item 1",number: "1")
    
    // set the "callback' closure
    cell.callback = { (val) in
        print("Stepper in cell at \(indexPath) changed to: \(val)")
        // do what you want when the stepper value was changed
        //  such as updating your data array
    }

    return cell
}

,

将委托用于通用方法。这样可以灵活地实现单元格与表格视图的交互方式，并实现Swift所期望的类型检查。

通常，对于UITableView，您将具有驱动单元内容的数据数组。就您而言，我们假设它是MyStruct（在视图控制器内部）：

struct MyStruct {
    let name: String
    var value: Int
}
var myStructs: [ MyStruct ] = [
    MyStruct( name: "Name 1",value: 1 ),MyStruct( name: "Name 2",value: 2 ),MyStruct( name: "Name 3",value: 3 ) ]

创建MyCellDelegate，并在其中放置将更改从单元格传递到视图控制器所需的任何方法。例如：

protocol MyCellDelegate: class {
    func didSet( value: Int,for myStructIndex: Int )
}

class MyCell: UITableViewCell {
    weak var delegate: MyCellDelegate!
    var myStructIndex: Int!
    ...
}

对于表视图，在使单元出队时分配委托，并实现协议。

class ViewController: MyCellDelegate,UITableViewDelegate,UITableViewDataSource {
    func tableView( _ tableView: UITableView,cellForRowAt indexPath: IndexPath ) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.identifier,for: indexPath) as! MyCell
        let myStruct = myStructs[indexPath.row]  // You may want to ensure that you are in bounds
        cell.delegate = self
        cell.myStructIndex = indexPath.row
        cell.configure( with: myStruct.name,number: myStruct.value )
        return cell
    }

    func didSet( value: Int,for myStructIndex: Int ) {
        //  Now MyViewController sees the change.
        myStructs[myStructIndex].value = value
    }
}

最后，在MyCell中，每当值更改时（例如在步进器中），都调用：

@IBAction func stepperChanged( _ sender: UIStepper ) {
    let integerValue = Int( sender.value.round() )
    numLabel.text = "\(integerValue)"

    //  Tell the view controller about the change: what happened,and to what cell.
    self.delegate.didSet( value: integerValue,for: self.myStructIndex )
}