Use of Unresolved Identifier with Segmented Control - ios

Question

I have a scene in my app that I want to do basic math between two slider bars and a segmented control that the user picks. I am trying to do the math between variables under the segmented controls, but Xcode is giving me a (!) stating
Use of unresolved identifier "xxxx"
with whatever variable I'm trying to add.
My code is:
import UIKit
class DopamineCalculator: UIViewController {
//slider outlets
#IBOutlet weak var slider: UISlider!
#IBOutlet weak var sliderone: UISlider!
//segmentoutlet
#IBOutlet weak var segmentoutlet: UISegmentedControl!
//LABELS
//weight label
#IBOutlet weak var weightlabel: UILabel!
//dosage label
#IBOutlet weak var dosagemg: UILabel!
//Drip Rate Answer Label
#IBOutlet weak var dripanswer: UILabel!
//ACTIONS!!
//weight slider action
#IBAction func weightslider(sender: UISlider) {
let weight = Int(sender.value)
//converts to kgs
let kgs = Int(sender.value) / Int(2.2)
weightlabel.text = "\(weight) lbs"
}
//Dosage Desired dosage slider
#IBAction func dosagedesired(sender: UISlider) {
let dosage = Int(sender.value)
dosagemg.text = "\(dosage) mg"
}
//CONCENTRATION OPTIONS
#IBAction func concentrationoption(sender: UISegmentedControl) {
switch segmentoutlet.selectedSegmentIndex
{
case 0:
dripanswer.text = (kgs) * (dosage) / 800
case 1:
dripanswer.text = "1600";
case 2:
dripanswer.text = "3200";
default:
break;
}
}
What I am trying to do is kgs x dosage / 800 respectively for each case. I can not find an adequate solution online to the unresolved identifier issue.

Answer 1

#IBOutlet ...
// Add variables to be reachable for all methods
var dosage : Int = 0
var kgs : Double = 0.0
var divisor : Double = 800.0
#IBAction func dosagedesired(sender: UISlider) {
// prepend self to variable as it is used
self.dosage = Int(sender.value)
dosagemg.text = "\(self.dosage) mg"
// adding the calculation here
let result = self.kgs * Double(self.dosage) / self.divisor
dripanswer.text = "\(result)"
}
#IBAction func weightslider(sender: UISlider) {
let weight = Int(sender.value)
// converts to kgs
// the same here
self.kgs = Int(sender.value) / Int(2.2)
// adding the calculation here
let result = self.kgs * Double(self.dosage) / self.divisor
dripanswer.text = "\(result)"
}
#IBAction func concentrationoption(sender: UISegmentedControl) {
switch segmentoutlet.selectedSegmentIndex
{
case 0:
self.divisor = 800.0
case 1:
self.divisor = 1600.0
case 2:
self.divisor = 3200.0
default:
self.divisor = 800.0
}
// finally the calculation
let result = self.kgs * Double(self.dosage) / self.divisor
dripanswer.text = "\(result)"
}

Answer 2

You should declare the variables kgs and dosage outside of any method i.e. at the class level, along with your outlets
//slider outlets
#IBOutlet weak var slider: UISlider!
#IBOutlet weak var sliderone: UISlider!
//segmentoutlet
#IBOutlet weak var segmentoutlet: UISegmentedControl!
//LABELS
//weight label
#IBOutlet weak var weightlabel: UILabel!
//dosage label
#IBOutlet weak var dosagemg: UILabel!
//Drip Rate Answer Label
#IBOutlet weak var dripanswer: UILabel!
// You should declare the variables here:
var kgs = 0
var dosage = 0
And when you use kgs and dosage inside your methods, remove the word let because you're not declaring a variable.
The reason you do this is that you can't access variables declared in a method in another method. In the concentrationoption method, you can't access dosage, which is defined in dosagedesired method.