Getting a total for values in cells - ios

Question

I have a table view that keeps track of hotel receipts (each time the user enters the date, cost, and name of the hotel and hits the add button it adds a new row to the table with the information.
I have 2 text fields below the table that I want to show the total entries (number of rows) and the sum of the cost field. Problem is I can't figure out how to do this or if it is even possible.
I have found a couple posts about it but they all seem to have a set number of rows.
extension HotelViewController: UITableViewDataSource {
func numberOfSections(in tableView: UITableView) -> Int {
let numberOfSections = frc.sections?.count
return numberOfSections!
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let numberOfRows = frc.sections?[section].numberOfObjects
return numberOfRows!
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "HotelCell", for: indexPath) as! HotelTableViewCell
let item = frc.object(at: indexPath) as! DriveAwayHotel
cell.date.text = item.date
cell.name.text = item.name
cell.cost.text = "$\(item.cost ?? 0.00)"
return cell
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
let managedObject : NSManagedObject = frc.object(at: indexPath) as! NSManagedObject
pc.delete(managedObject)
do {
try pc.save()
} catch {
print(error)
return
}
}

Answer 1

You should not try to do math on your cells. You should do math on your model.
Are you trying to sum all the entries in your table, or just the cells that are visible?
If you want to sum all the entries in your table view, then loop through all the sections in your frc.sections array, loop through all the entries in each section, and add them all up. (That code would be easy to write.)
If you only want to sum the entries for the currently visible cells, call the table view's indexPathsForVisibleRows method to get an array of the indexPaths of the cells that are visible, loop through those indexPaths, fetch the entry at each section and row, and add those together. (That code would also be easy to write.)
EDIT:
The code to sum all your entries might look something like the below (I'm having to guess a bit since I don't know your data model)
var total = 0.0
guard let sections = frc.sections?.count else { return }
for section in 0..<sections {
guard let rows = frc.sections?[section].numberOfObjects else { continue }
for row in 0..<rows {
let indexPath = IndexPath(row: row, section: section)
let item = frc.object(at: indexPath) as! DriveAwayHotel
total += item.cost
}
}