Calculating sum until the indexPath.row instead of total using tableView - ios

Question

I had a question about calculation functions and I cant seem to understand the logic behind it yet as I just started to do coding in iOS about 3 months ago.
Here's a screenshot in the link and please take a look at it.
I would like to achieve results as explained Below
Expected Results : there will be more than 10000 cell of rows eventually, so my sum Cell will required to calculate based on the first index of the data instead of cell, I tried enumerated, mapping, for in loops but to no success
.
PLEASE PROVIDE CODE ALONG WITH YOUR EXPLANATION SO I CAN UNDERSTAND AS I AM NOT AN EXPERIENCED CODER
Example
UIVIEW
TotalBalance = $ 28.00 << Achieve by updateTotal()
TableView
TransactionType : $ 10.00 ($10.00) < this will sum cell 1 only as it is the first cell
TransactionType : $ 5.00 ($15.00) < this will sum cell 1 - 2 only
TransactionType : $ 3.00 ($18.00) < this will sum cell 1 - 3 only
TransactionType : $ 10.00 ($28.00) < this will sum cell 1 - 4 only
class Account: Object {
#objc dynamic var name : String = ""
#objc dynamic var balance : Double = 0
var ofTransaction = List<Transaction>()
}
class Transaction: Object {
#objc dynamic var name : String = ""
#objc dynamic var amount : Double = 0
var parentAccount = LinkingObjects(fromType: Account.self, property: "ofTransaction")
}
class AccountCell: UITableViewCell {
#IBOutlet weak var name: UILabel!
#IBOutlet weak var amount: UILabel!
#IBOutlet weak var sum: UILabel!
}
func updateTotal() {
let total = getTransactions
.map { $0.amount }
.reduce(0, +)
let totalFormatter = NumberFormatter()
totallabel.text = totalFormatter.string(for: total)!
}
override func viewDidLoad() {
super.viewDidLoad()
account = realm.objects(Account.self)
getTransactions = realm.objects(Transaction.self)
}
// MARK: - Table view data source
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! AccountCell
if let transCell = getTransactions?[indexPath.row] {
cell.name.text = transCell.name
cell.amount.text = "\(transCell.amount)"
///Wrong Logic : This logic updates the Sum to Total !
let sumCell = getTransactions
.map { $0.amount }
.reduce(0, +)
cell.sum.text = "\(sumCell)"
}
return cell
}

Answer 1

Use it like below-
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! AccountCell
if let transCell = getTransactions?[indexPath.row] {
cell.name.text = transCell.name
cell.amount.text = "\(transCell.amount)"
//Correct calculation in Loops
var sumUp = 0.0
for (index,trans) in getTransactions.enumerated() {
if (index == indexPath.row) { break }
sumUp += trans.amount
cell.sum.text = "\(sumUp)"
}
}
return cell
}