ios - 每个表格 View 单元格一个计时器

Question

我想点击表格单元格并启动计时器。每个单元格都应该有自己的计时器。我设法设置了计时器，但不是独立设置的，当我设置一个时，所有单元格都已设置。

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

    let currentCell = tableView.cellForRow(at: indexPath) as! StaffTableViewCell

    if isRunning == false {



        currentCell.cellImageView.image = UIImage(data: UIImagePNGRepresentation(#imageLiteral(resourceName: "greendot"))!)


        timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in

            counter += 1
            let hourPortion = String(format: "%02d", counter / 3600)
            let minutesPortion = String(format: "%02d", counter / 60)
            let secondsPortion = String(format: "%02d", counter % 60)
            //print("\(hourPortion):\(minutesPortion):\(secondsPortion)")

            timeTotal = "\(hourPortion):\(minutesPortion):\(secondsPortion)"

            currentCell.timerLabel.text = timeTotal


            isRunning = true

        }


    }

    tableView.reloadData()


}

func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) {

    timer.invalidate()
    isRunning = false

    let currentCell = tableView.cellForRow(at: indexPath) as! StaffTableViewCell

    if let data = UIImagePNGRepresentation(#imageLiteral(resourceName: "reddot")) {
        currentCell.cellImageView.image = UIImage(data: data)
    }



    tableView.reloadData()
}

Answer 1

我会这样做:

• 创建一个结构来表示包含开始时间以及该行当前是否正在运行的每一行
• 安排一个 0.5 秒的重复计时器以解决 Timer
中的抖动
• 每次计时器触发时，更新具有“正在运行”计时器的可见行

import UIKit

struct TimerModel {
    private var startTime: Date?
    private var offset: TimeInterval = 0

    var elapsed : TimeInterval {
        get {
            return self.elapsed(since:Date())
        }
    }

    var isRunning = false {
        didSet {
            if isRunning  {
                self.startTime = Date()
            } else {
                if self.startTime != nil{
                    self.offset = self.elapsed
                    self.startTime = nil
                }
            }
        }
    }

    func elapsed(since: Date) -> TimeInterval {
        var elapsed = offset
        if let startTime = self.startTime {
            elapsed += -startTime.timeIntervalSince(since)
        }
        return elapsed
    }
}

class ViewController: UIViewController {

    @IBOutlet weak var tableview: UITableView!

    var timer: Timer?
    var timersActive = 0

    let formatter: DateComponentsFormatter = {
        let formatter = DateComponentsFormatter()
        formatter.zeroFormattingBehavior = .pad
        formatter.allowedUnits = [.hour, .minute, .second]
        return formatter
    }()

    var timers = [TimerModel](repeating:TimerModel(), count:30)


    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func elapsedTimeSince(_ startTime: Date) -> String {
        let elapsed = -startTime.timeIntervalSinceNow

        return self.formatter.string(from: elapsed) ?? "0:00:00"
    }

    func startTimer() {
        self.timersActive += 1
        guard self.timer == nil else {
            return
        }

        self.timer = Timer.scheduledTimer(withTimeInterval: 0.5, repeats: true, block: { [weak self] (timer) in
           if let me = self {
            for indexPath in me.tableview.indexPathsForVisibleRows ?? [] {
                let timer = me.timers[indexPath.row]
                if timer.isRunning {
                    if let cell = me.tableview.cellForRow(at: indexPath) {
                        cell.textLabel?.text = me.formatter.string(from: timer.elapsed) ?? "0:00:00"
                    }
                }
            }
           }
        })
    }

    func stopTimer() {
        self.timersActive -= 1
        if self.timersActive == 0 {
            self.timer?.invalidate()
            self.timer = nil
        }
    }

}

extension ViewController: UITableViewDataSource {
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.timers.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
        let timer = self.timers[indexPath.row]

        cell.imageView?.image = timer.isRunning ? #imageLiteral(resourceName: "GreenDot") : #imageLiteral(resourceName: "RedDot")
        cell.textLabel?.text = self.formatter.string(from: timer.elapsed) ?? "0:00:00"

        return cell
    }
}

extension ViewController: UITableViewDelegate {
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        self.timers[indexPath.row].isRunning = !self.timers[indexPath.row].isRunning
        self.tableview.reloadRows(at: [indexPath], with: .none)
        if self.timers[indexPath.row].isRunning {
            self.startTimer()
        } else {
            self.stopTimer()
        }
    }
}