I cant get my calculations print in the label - ios

Question

I am trying to get the values to calculate the profit and print out the calculated numbers in a label, but it isn't printing it out in the label. When I hover over "outputValue" after the app crashed it has the calculated value stored in it, but for some reason it doesn't print out in the label and gives me the error
Cannot assign value of type 'Double' to type 'String?'
at line ProfitLabel.text = (outputValue) in insertNewItems(). Is there any way to fix this?
import UIKit
import SafariServices
class ViewController: UIViewController, UIAdaptivePresentationControllerDelegate, UITextFieldDelegate, UITableViewDataSource {
#IBOutlet weak var tableView: UITableView!
#IBOutlet weak var OrderNumberLabel: RoundedLabel2!
#IBOutlet weak var CostLabel: RoundedLabel2!
#IBOutlet weak var ProfitLabel: RoundedLabel2!
#IBOutlet weak var TotalLabel: RoundedLabel2!
#IBOutlet weak var itemTextField: UITextField!
#IBOutlet weak var priceTextField: UITextField!
#IBOutlet weak var saleTextField: UITextField!
var items: [ItemRow] = []
struct ItemRow: Codable
{
var first: String
var second: String
var third: String
}
override func viewDidLoad() {
super.viewDidLoad()
load()
// tableView.tableFooterView = UIView(frame: CGRect.zero)
}
func save(){
if let data = try? PropertyListEncoder().encode(items) {
UserDefaults.standard.set(data, forKey: "SavedItems")
}
}
func load(){
let defaults = UserDefaults.standard
if let data = defaults.data(forKey: "SavedItems") {
items = try! PropertyListDecoder().decode([ItemRow].self, from: data)
}
}
#IBAction func addButtonTapped(_ sender: Any) {
insertNewItems()
save()
}
func insertNewItems() {
let newVideoRow = ItemRow(first: itemTextField.text!, second: priceTextField.text!, third: saleTextField.text!)
items.append(newVideoRow)
let indexPath = IndexPath(row: items.count - 1, section: 0)
tableView.beginUpdates()
tableView.insertRows(at: [indexPath], with: .automatic)
tableView.endUpdates()
let priceValue = Double(priceTextField.text!)
let saleValue = Double(saleTextField.text!)
if priceValue != nil && saleValue != nil {
let outputValue = Double (saleValue! - priceValue!)
ProfitLabel.text = (outputValue)
}
itemTextField.text = ""
priceTextField.text = ""
saleTextField.text = ""
view.endEditing(true)
}
}
extension ViewController: UITableViewDelegate{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let ItemTitle = items[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: "ItemCell") as! ItemCell
cell.itemLabel.text = ItemTitle.first
cell.priceLabel.text = ItemTitle.second
cell.saleLabel.text = ItemTitle.third
return cell
}
func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
return true
}
func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
items.remove(at: indexPath.row)
tableView.beginUpdates()
tableView.deleteRows(at: [indexPath], with: .automatic)
tableView.endUpdates()
save()
}
}
}

Answer 1

Simply disconnect you ProfitLabel and reconnect the outlet.
Also try convert output value to string like this:
ProfitLabel.text = "\(output)"

Answer 2

The error is clear: You are going to assign a Double to a text property which is impossible.
There is an easy solution
ProfitLabel.text = String(outputValue)
However your code is cumbersome and objective-c-ish, the recommended Swift syntax is
if let priceValue = Double(priceTextField.text!),
let saleValue = Double(saleTextField.text!) {
ProfitLabel.text = String(saleValue - priceValue)
}
If the code still crashes then the text field ProfitLabel is not connected in Interface Builder.
Side notes:
Please name variables according to the naming convention with starting lowercase letter.
Delete beginUpdates/endUpdates. Both lines have no effect.

Answer 3

ProfitLabel.text = NSString(format: "%.2f", outputValue) as String
it will round off up to 2 decimal places convert double into the string

Answer 4

You are force unwrapping the values. Replace following code
let priceValue = Double(priceTextField.text!)
let saleValue = Double(salesTextField.text!)
if priceValue != nil && saleValue != nil {
let outputValue = Double (saleValue! - priceValue!)
ProfitLabel.text = (outputValue)
}
With
if let price = Double(priceTextField.text ?? ""), let sale = Double(salesTextField.text ?? "") {
let outputValue = price - sale
ProfitLabel.text = String(outputValue)
} else {
print("Getting nil for \(priceTextField.text) or \(salesTextField.text)")
}

Answer 5

if priceValue != nil && saleValue != nil {
let profit = Double(saleValue)! - Double(priceValue)!
ProfitLabel.text = profit
}