在 swift 中选择和取消选择表格视图单元格时遇到问题

Question

我在表格视图中显示密码，当我 select 一个单元格时，它应该 select 如果我再次点击同一个单元格，那么它应该 deselect( 而点击单元格应该像开关一样工作）

但使用以下代码

问题 1： 最初我无法 select 第一行，但在 select 任何其他行之后，然后能够 select第一行.. 为什么？我哪里错了？

问题 2： 只有一次我可以 select deselect 同一行两次点击如果我连续点击第三次然后无法 select同一行，为什么？..请指导

class PincodeModel{
var name: String?
var id: Int?
var isSelected: Bool

init(name: String?, id: Int?, isSelected: Bool) {
    self.name = name
    self.id = id
    self.isSelected = isSelected
}
}


class FilterViewController: UIViewController {

var pincodePreviousIndex: Int = -1
var pincodes = [PincodeModel]()

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    
    for pincode in pincodeList {
        self.pincodes.append(PincodeModel(name: pincode, id: 0, isSelected: false))
    }
}


func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "SubFilterTableViewCell", for: indexPath) as! SubFilterTableViewCell
        cell.title.text = self.pincodes[indexPath.row].name

        if !self.pincodes.isEmpty {
            if self.pincodes[indexPath.row].isSelected == true {
                cell.tickImageView.image =  #imageLiteral(resourceName: "iconTick")
            }else {
                cell.tickImageView.image = UIImage()
            }
        }
    return cell
}

 // EDITED Code according to below answer
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
   
    self.pincodes[indexPath.row].isSelected = !self.pincodes[indexPath.row].isSelected

if self.pincodes[indexPath.row].isSelected == true {
self.filterData.pincode = pincodes[indexPath.row].name ?? ""
}else {
self.filterData.pincode = ""
}
if pincodePreviousIndex > 0 && pincodePreviousIndex != indexPath.row {
pincodes[pincodePreviousIndex].isSelected = false
}
pincodePreviousIndex = indexPath.row

}

当我从索引 = 1 select 时，这是我想要的，但是如果我 select 第一行（索引 = 0），那么正确的标记仍然存在，如果我 select又一行，为什么？

o/p 编辑代码：

Answer 1

对于问题 1 - 通过使用这行代码：

var pincodePreviousIndex: Int = 0

你不能点击第一行，直到你点击另一行，因为

pincodes[pincodePreviousIndex].isSelected = false

由于您一开始默认为 0，因此与第一行相关。

对于问题 2 - 如果您 select 第 2 行 (selected) 然后 select 再次删除 select 它：pincodePreviousIndex 将保存值该行然后用

再次删除select

pincodes[pincodePreviousIndex].isSelected = false

因此，即使您正在 select 它也会删除 select 它。

我会在顶部这样做： var pincodePreviousIndex: Int = -1

在底部：

if pincodePreviousIndex > 0 && pincodePreviousIndex != indexPath.row {
    pincodes[pincodePreviousIndex].isSelected = false
}

Answer 2

您可以采取一些方法来避免一些麻烦。

首先，在您的单元格上设置 .selectionStyle = .none，然后在您的单元格 class 中覆盖 setSelected(...)。例如，我向我的单元格添加了一个图像视图，并给它一个空框作为它的图像，一个选中框作为它的突出显示图像：

override func setSelected(_ selected: Bool, animated: Bool) {
    super.setSelected(selected, animated: animated)
    imgView.isHighlighted = selected ? true : false
}

现在单元格外观将反映其 selected 状态，该状态由 table 视图维护。

接下来，我们将实施 willSelectRowAt 而不是 didSelectRowAt ...如果单元格当前是 selected，我们将取消select 它（并更新我们的数据）：

func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
    // is a row already selected?
    if let idx = tableView.indexPathForSelectedRow {
        if idx == indexPath {
            // tapped row is already selected, so
            //  deselect it
            tableView.deselectRow(at: indexPath, animated: false)
            //  update our data
            pincodes[indexPath.row].isSelected = false
            //  tell table view NOT to select the row
            return nil
        } else {
            // some other row is selected, so
            //  update our data
            //  table view will automatically deselect that row
            pincodes[idx.row].isSelected = false
        }
    }
    // tapped row should now be selected, so
    //  update our data
    pincodes[indexPath.row].isSelected = true
    //  tell table view TO select the row
    return indexPath
}

这是一个完整的例子：

class PincodeModel{
    var name: String?
    var id: Int?
    var isSelected: Bool
    
    init(name: String?, id: Int?, isSelected: Bool) {
        self.name = name
        self.id = id
        self.isSelected = isSelected
    }
}

class SelMethodTableViewController: UIViewController {

    var pincodes: [PincodeModel] = []
    
    let tableView = UITableView()
    
    let infoView: UIView = {
        let v = UILabel()
        v.backgroundColor = UIColor(white: 0.9, alpha: 1.0)
        return v
    }()
    let infoTitle: UILabel = {
        let v = UILabel()
        v.text = "Info:"
        return v
    }()
    let infoLabel: UILabel = {
        let v = UILabel()
        v.numberOfLines = 0
        return v
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        for i in 0..<20 {
            let pcm = PincodeModel(name: "\(i)", id: i, isSelected: false)
            pincodes.append(pcm)
        }

        [tableView, infoView, infoTitle, infoLabel].forEach { v in
            v.translatesAutoresizingMaskIntoConstraints = false
        }
        [infoTitle, infoLabel].forEach { v in
            infoView.addSubview(v)
        }
        [tableView, infoView].forEach { v in
            view.addSubview(v)
        }
        
        let g = view.safeAreaLayoutGuide
        
        NSLayoutConstraint.activate([
            
            // constrain the table view on right-side of view
            tableView.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
            tableView.widthAnchor.constraint(equalTo: g.widthAnchor, multiplier: 0.5),
            tableView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            tableView.bottomAnchor.constraint(equalTo: infoView.topAnchor, constant: -16.0),

            // let's add a tappable "info" view below the table view
            infoView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 20.0),
            infoView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -20.0),
            infoView.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -20.0),
            infoView.heightAnchor.constraint(equalToConstant: 120.0),
            
            // add labels to infoView
            infoTitle.topAnchor.constraint(equalTo: infoView.topAnchor, constant: 8.0),
            infoTitle.leadingAnchor.constraint(equalTo: infoView.leadingAnchor, constant: 8.0),
            infoTitle.trailingAnchor.constraint(equalTo: infoView.trailingAnchor, constant: -8.0),
            infoLabel.topAnchor.constraint(equalTo: infoTitle.bottomAnchor, constant: 8.0),
            infoLabel.leadingAnchor.constraint(equalTo: infoView.leadingAnchor, constant: 8.0),
            infoLabel.trailingAnchor.constraint(equalTo: infoView.trailingAnchor, constant: -8.0),
            //infoLabel.bottomAnchor.constraint(lessThanOrEqualTo: infoView.bottomAnchor, constant: -8.0),
            
        ])

        tableView.dataSource = self
        tableView.delegate = self
        
        tableView.register(MyToggleCell.self, forCellReuseIdentifier: "toggleCell")
        
        // just so we can see the frame of the table view
        tableView.layer.borderWidth = 1.0
        tableView.layer.borderColor = UIColor.red.cgColor

        let t = UITapGestureRecognizer(target: self, action: #selector(showInfo(_:)))
        infoView.addGestureRecognizer(t)
        infoView.isUserInteractionEnabled = true
    }

    @objc func showInfo(_ g: UIGestureRecognizer) -> Void {
        var s: String = ""
        
        let selectedFromData = pincodes.filter( {[=12=].isSelected == true} )

        s += "Data reports:"
        if selectedFromData.count > 0 {
            selectedFromData.forEach { ob in
                let obID = ob.id ?? -1
                s += " \(obID)"
            }
        } else {
            s += " Nothing selected"
        }
        s += "\n"
        s += "Table reports: "
        if let selectedFromTable = tableView.indexPathsForSelectedRows {
            selectedFromTable.forEach { idx in
                s += " \(idx.row)"
            }
        } else {
            s += " No rows selected"
        }
        infoLabel.text = s
    }
}

extension SelMethodTableViewController: UITableViewDataSource, UITableViewDelegate {
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return pincodes.count
    }
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let c = tableView.dequeueReusableCell(withIdentifier: "toggleCell", for: indexPath) as! MyToggleCell
        c.label.text = pincodes[indexPath.row].name
        c.selectionStyle = .none
        return c
    }
    func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
        // is a row already selected?
        if let idx = tableView.indexPathForSelectedRow {
            if idx == indexPath {
                // tapped row is already selected, so
                //  deselect it
                tableView.deselectRow(at: indexPath, animated: false)
                //  update our data
                pincodes[indexPath.row].isSelected = false
                //  tell table view NOT to select the row
                return nil
            } else {
                // some other row is selected, so
                //  update our data
                //  table view will automatically deselect that row
                pincodes[idx.row].isSelected = false
            }
        }
        // tapped row should now be selected, so
        //  update our data
        pincodes[indexPath.row].isSelected = true
        //  tell table view TO select the row
        return indexPath
    }
}

class MyToggleCell: UITableViewCell {
    let imgView: UIImageView = {
        let v = UIImageView()
        return v
    }()
    let label: UILabel = {
        let v = UILabel()
        return v
    }()
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        commonInit()
    }
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }
    func commonInit() -> Void {
        [imgView, label].forEach { v in
            v.translatesAutoresizingMaskIntoConstraints = false
            contentView.addSubview(v)
        }
        let g = contentView.layoutMarginsGuide
        
        // give bottom anchor less-than-required
        //  to avoid auto-layout complaints
        let b = imgView.bottomAnchor.constraint(equalTo: g.bottomAnchor, constant: -4.0)
        b.priority = .required - 1
        
        NSLayoutConstraint.activate([
            imgView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 0.0),
            imgView.topAnchor.constraint(equalTo: g.topAnchor, constant: 4.0),
            imgView.widthAnchor.constraint(equalToConstant: 32.0),
            imgView.heightAnchor.constraint(equalTo: imgView.widthAnchor),
            b,
            
            label.centerYAnchor.constraint(equalTo: g.centerYAnchor, constant: 0.0),
            label.leadingAnchor.constraint(equalTo: imgView.trailingAnchor, constant: 16.0),
            label.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: 0.0),
        ])
        if let img1 = UIImage(systemName: "square"),
           let img2 = UIImage(systemName: "checkmark.square") {
            imgView.image = img1
            imgView.highlightedImage = img2
        }
    }

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
        imgView.isHighlighted = selected ? true : false
    }
}

它看起来像这样：

当运行:

点击一行将 select 该行
点击不同的行将 select 新行并取消 select 当前 select 编辑的行
点击已经select编辑的行将删除select它
点击灰色的“信息视图”将报告来自数据和 table 视图的 select 离子状态

请注意，如果 selected 行滚动到视图之外，它将保持 selected（并且在滚动回视图时将显示 selected）并且数据和 table 视图 select 离子状态将继续正确。

编辑

如果我们想使用 didSelectRowAt（也许用于其他用途），我们可以像这样“切换”selected 行：

func tableView(_ tableView: UITableView, willSelectRowAt indexPath: IndexPath) -> IndexPath? {
    
    // if the tapped row is already selected
    if let indexPathForSelectedRow = tableView.indexPathForSelectedRow,
       indexPathForSelectedRow == indexPath {
        tableView.deselectRow(at: indexPath, animated: false)
        // calling .deselectRow(at: ...) does NOT trigger a call to didDeselectRowAt
        // so update our data here
        pincodes[indexPath.row].isSelected = false
        return nil
    }
    return indexPath
    
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    print("did select", indexPath)
    pincodes[indexPath.row].isSelected = true
}
func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {
    print("did deselect", indexPath)
    pincodes[indexPath.row].isSelected = false
}

在 swift 中选择和取消选择表格视图单元格时遇到问题

Facing issue in selecting and deselecting tableview cell in swift

ios

swift

uitableview

select

deselect