How to iterate a for loop in table view cell swift

Question

I tried this but not worked Iterate over all the UITableCells given a section id I need to just iterate a for loop in cell and calculate the value and display in another label calculated_value or print I dont know how to do it. Any help will be great! I got only value for cell I see the cell which are at bottom there value is not calculated. when I scroll up I get the cell value but then the top cell value is not able to see or calculate.

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource{
  let news = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10"]
  func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    return news.count
  }

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

    let cell = myTableView.dequeueReusableCell(withIdentifier: "mycellTVC") as! mycellTVC
    cell.lbl.text = news[indexPath.row]

    return cell
  }


  func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 80
  }

  @IBOutlet weak var myTableView: UITableView!

  override func viewDidLoad() {
    super.viewDidLoad()
    myTableView.delegate = self
    myTableView.dataSource = self

  } 
}
 **This is my cell file**
class mycellTVC: UITableViewCell{

  @IBOutlet weak var lbl: UILabel!
  @IBOutlet weak var calculated_value: UILabel!
}

I don't see any calculation in your code. What is that you want to achieve ? — Nitish, Apr 26 '18 at 12:54
Please check I have editied and it creates issue when I the cell is below and I am not able to get it's value not calculate — arman khan, Apr 26 '18 at 12:55
Could you clarify what are you aiming to do? the table view has only one section containing `news.count` as number of rows and your code should work fine so far... — Ahmad F, Apr 26 '18 at 12:56
To be more clear I want to get the addition of all value in label for all 10 rows print or another label by using for loop. — arman khan, Apr 26 '18 at 13:03
tinyurl.com/yd9cracg <-this is link you can check this image as we have two in image for ex if we have 20 items and get the addition of all in label that calculate the actual price $226 — arman khan, Apr 26 '18 at 13:13
dont try calculations based on UI element value in a cell. use the data source to do it — Scriptable, Apr 26 '18 at 13:26
@Scriptable I don't know how . Please share something to get it worked — arman khan, Apr 26 '18 at 13:29
you need to clarify exactly what you want. You want total of numbers in news array? so in this case result would be 55? — Scriptable, Apr 26 '18 at 13:44
@Scriptable I have 10 rows and I have one label in cell on which I pass value from api and I want calculate that value and display in another label is my goal . same as we do in shopping app on order screen and please copy and paste check this link tinyurl.com/yd9cracg you will get to know what I am exactly trying to say — arman khan, Apr 26 '18 at 13:48

score 0 · Accepted Answer · answered Apr 26 '18 at 14:08

0

The basics of what you are trying to do are to get a value from the data source, convert it to a number if needed and then total them up.

For your example above, this would do the trick:

let news = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10"]

let total = news.map({ Int($0)! }).reduce(0) { x, y in
    return x + y
}

print(total) // 55

To do this for a shopping cart, your data source will likely be a list of products instead, maybe something like:

struct Product
{
    var name: String
    var price: Int
    var quantity: Int
}

let prod1 = Product(name: "Coka Cola", price: 2, quantity: 2)
let prod2 = Product(name: "Bread", price: 1, quantity: 1)
let prod3 = Product(name: "Sweets", price: 2, quantity: 4)

let shoppingCart = [prod1, prod2, prod3]

let total = shoppingCart.reduce(0) { x, y in
    return x + (y.price * y.quantity)
}

print(total) // 13

Its the same principal, just a little more complicated. As long as your data structure is right it should be straight forward

answered Apr 26 '18 at 14:08

Scriptable

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it worked and thank you. I have a confusion for example If i have 3 text field like name A, B, C in each row and 10 rows . I am performing some calculation A*B result is stored in C . I am passing value to B from API but after editing the B when I scroll up and down it gives same value which I got from API. How can I append the live edited value and pass it to text Field – arman khan Apr 26 '18 at 14:17
when you change any values you should be updating the underlying data. Cells in a collection/tableview can be reused when not in view. so if you have large cells for example you might only fit 5 on screen. you might only have 5 loaded at all, maybe 6. so if you update values in a cell and then its unloaded and reused for another one. then you lose your data. so always rely on DATA not the UI – Scriptable Apr 26 '18 at 14:27
thank you . I tried with data I run a for loop in table view cell to get all data my table view screen fits only 2 cell at a time and other cell are below. So I get data for first 2 cell and for other cell below I get "NIL" I tried many solutions but not worked – arman khan Apr 27 '18 at 05:30
**you cannot get data from invisible cells** (you could.. but you really, really shouldn't) use the underlying data. you create a cell on demand from data, if you update the data in a cell, update the data too. always do calculations on the data, not the cell itself – Scriptable Apr 27 '18 at 06:14
Check this answer to see how to do update the data after editing: https://stackoverflow.com/questions/32669759/update-array-while-editing-cell-while-running-the-app – Scriptable Apr 27 '18 at 06:25
That was great I tried and it worked. I get the value proper and now it doesn't reload the older value I get new values. – arman khan Apr 27 '18 at 11:33

How to iterate a for loop in table view cell swift

1 Answers1