Multiple Timers in Tableview Swift - ios

Question

I am trying to have timer for each row which is added manually when user clicks on add button.
Start time is set to 100units(not important for the question) and it should count down.
When new row is added it will have it's own timer started and display the value on this new row.
I tried to have timer in each cell but this is creating issue when dequeuing, so I created array of timer to hold corresponding timer for each cell. Problem I am facing right now is how to update the cell value every second(timer interval)
MultipleTimersTableView_Gist is the link for the code I wrote so far. I thought of using delegate to update the cell but not sure with the best approach.
Any help would be appreciated.
EDIT:
Timers should show the time in increasing order because each row is created(along with timer)from top to bottom meaning first will have less time than next. Looks like while dequeueing something messed up.
Here is the gist I used for above screenshot

Answer 1

Here is how you can handle timers in each UITableViewCell.
Create a custom UITableViewCell
class CustomCell: UITableViewCell {
//MARK: Outlets
#IBOutlet weak var label: UILabel!
//MARK: Internal Properties
var handler: ((Int)->())?
//MARK: Private Properties
private var timer: Timer?
private var counter = 100 {
didSet {
DispatchQueue.main.async {
self.label.text = "\(self.counter)"
self.handler?(self.counter)
}
}
}
//MARK: Internal Methods
func configure(with counter: Int) {
self.counter = counter
self.setTimer()
}
//MARK: Private Methods
private func setTimer() {
self.timer?.invalidate()
self.timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true, block: {[weak self] (timer) in
if let counter = self?.counter, counter > 0 {
self?.counter -= 1
} else {
timer.invalidate()
}
})
}
}
In the above code,
I've created a label that will update the counter value in UI.
handler - it will and store the updated counter value somewhere (in ViewController, explained further) when the cell is moved out of the screen
timer - schedule the timer in the cell with timeinterval = 1
counter - current counter value for each cell
In the ViewController,
class VC: UIViewController, UITableViewDataSource {
let numberOfCells = 20
var timerArr = [Int]()
override func viewDidLoad() {
super.viewDidLoad()
self.timerArr = [Int](repeating: 100, count: numberOfCells)
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return self.numberOfCells
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! CustomCell
cell.configure(with: self.timerArr[indexPath.row])
cell.handler = {[weak self] (counter) in
self?.timerArr[indexPath.row] = counter
}
return cell
}
}
In the above code,
timerArr - keeps track of the counter value for each cell in the tableView.
In tableView(_:cellForRowAt:), the counter for each cell is updated using the handler we created previously in CustomCell.

Answer 2

I would use one timer for all the cells. When creating your object and adding it to the datasource, record the dateAdded = Date(), then when the cells are rebuilt on the timer fire, get the seconds count for each cell from the dateAdded field and update the cell in cellForRowAtIndex.