How can I perform addition automatically in iOS? - ios

Question

I work on a e-commerce project and now designing basket page. I create 4 steppers for determine to quantity of products. I create labels for show cost of each products and one label for total cost.
#IBOutlet weak var label1: UILabel!
#IBOutlet weak var label2: UILabel!
#IBOutlet weak var label3: UILabel!
#IBOutlet weak var label4: UILabel!
#IBOutlet weak var label5: UILabel!
#IBAction func GmS1(_ sender: GMStepper) {
label1.text = String(sender.value*1.5)
}
#IBAction func GmS2(_ sender: GMStepper) {
label2.text = String(sender.value*0.89)
}
#IBAction func GmS3(_ sender: GMStepper) {
label3.text = String(sender.value*26)
}
#IBAction func GmS4(_ sender: GMStepper) {
label4.text = String(sender.value*4)
}
I don't want to use button but I struggling in addition total cost automatically. My codes are above. Are there anybody know : How can ı addition 4 label in 1 label automatically(without any button).
Label5 for total cost.
You can check photo for general idea.

Answer 1

Make a function sumValues, add all the label's value in it, and assign string of sum to label5.text. This function can be then called from all the IBAction
#IBAction func GmS4(_ sender: GMStepper) {
label4.text = String(sender.value*4)
sumValues()
}
In the function sumValues(),
set label5.text = string of sum of all the labels'.
SideNote - Make sure to initialize value of all labels to 0 in viewDidLoad().

Answer 2

You can try to call this method from every action
func sumAll() {
let sum = [label1,label2,label3,label4].map { Int($0.text ?? "0" ) ?? 0 }.reduce(0,+)
label5.text = "\(sum)"
}
Note: if word variable is part of the label text you may extract number from the text or declare the steppers as outlets and ask them about their current value and at this way use
let sum = [stepper1,stepper2,stepper3,stepper4].map{$0.value}.reduce(0,+)

Answer 3

Continuing from your previous question:
#IBAction func gmstp1(_ sender: GMStepper) {
label1.text = String(sender.value * 1.5)
calculateSum()
}
#IBAction func gmstp2(_ sender: GMStepper) {
label2.text = String(sender.value * 0.89)
calculateSum()
}
#IBAction func gmstp3(_ sender: GMStepper) {
label3.text = String(sender.value * 26.0)
calculateSum()
}
#IBAction func gmstp4(_ sender: GMStepper) {
label4.text = String(sender.value * 4.0)
calculateSum()
}
Where calculateSum is a function defined like so:
func calculateSum() {
if let text1 = label1.text, let value1 = Double(text1),
let text2 = label2.text, let value2 = Double(text2),
let text3 = label3.text, let value3 = Double(text3),
let text4 = label4.text, let value4 = Double(text4) {
let sum = value1 + value2 + value3 + value4
label6.text = String(sum)
}
}
Or if you'd prefer a one-liner:
func calculateSum() {
label5.text = String([label1, label2, label3, label4].reduce(0,{$0 + (Double($1.text ?? "0") ?? 0)}))
}