How can I change a variable value using button/slider/touch action? - swift

Question

I am a student and very new to coding (Xcode with Swift language in this case).
I was trying to change a variable using a button/slider/gesture like this:
There are two variables (firstVariable & secondVariable) and set up a UIslider input that should define the value of the variables
I wanted the variables to be the same value of the slider/touchgesture but the variables remain 4 and 6 even after scrolling the slider in the simulator.
I think its because they are out of the scope of the slider function but how can I link them?
class MyViewController : UIViewController {
var firstVariable = 4
override func viewDidLoad() {
super.viewDidLoad()
var secondVariable = 6
print(secondVariable)
print(firstVariable)
let myslider = UISlider()
//create a UISLider
myslider.maximumValue = 100
myslider.minimumValue = 0
myslider.value = 30
myslider.frame = CGRect(x: 150, y: 200, width: 200, height: 40)
myslider.addTarget(self, action: #selector(sliderinput), for: UIControl.Event.valueChanged)
self.view.addSubview(myslider)
}
#objc func sliderinput(sender: UISlider) {
firstVariable = Int(sender.value)
secondVariable = Int(sender.value)
}
}
Thanks in advance!

Answer 1

First of all, take your secondVariable outside of the viewDidLoad as you cannot access it outside of viewDidLoad. To learn about scope read this. And you need to print the value of the variables to see the values are actually changing.
#objc func sliderinput(sender: UISlider) {
firstVariable = Int(sender.value)
secondVariable = Int(sender.value)
print(secondVariable)
print(firstVariable)
}

Answer 2

Sorry, this is the real context. I wanted to make an infinite timeline like the iOS calendar day tab or like a video editing software timeline for example.
I haven’t yet figured out how to get the distance from the beginning and end of the touch and how to link it to the scrollDistance variable on the beginning so I could create a scroll down effect and later a pinchgesturerecognizer to set the spacing/zoom between the lines.
I know I could use a UIscrollview or UIcollectionview but I felt it was good idea to create a custom one xD
Once again thanks for everyones support! :D
import UIKit
class ViewController: UIViewController {
let lineElements: Array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
let spacing: Int = 30 //spacing between elements
var scrollDistance = 90 // 90 for example, this should be the pangesture distance
//UIPanGestureRecogn function to determine the Y scroll distance from touch began to ended
#objc func touchinput (sender: UIPanGestureRecognizer) {
let touchlocation = sender.location(in: view)
var touchStart: CGPoint
var touchEnd: CGPoint
print("touch current location is", touchlocation)
if sender.state == UIGestureRecognizer.State.began {
touchStart = sender.location(in: view)
print("touch start", touchStart)
} else if sender.state == UIGestureRecognizer.State.ended {
touchEnd = sender.location(in: view)
print("touch end", touchEnd)
}
//I haven’t figure out how to get the distance between start and end and link it to the scrollDistance
//let scrollDistance = touchEnd.y - touchStart.y
}
override func viewDidLoad() {
super.viewDidLoad()
// ===================== Timeline a partir daqui =========================
let totalElements: Int = lineElements.count
for n in 1...totalElements {
let yPosition = lineElements[n - 1] * spacing + scrollDistance //Get Line heigh index times the spacing + scroll distance by touch pan gesture
let hourlabel = UILabel()
let linepath = UIBezierPath()
linepath.move(to: CGPoint(x: 60, y: yPosition))
linepath.addLine(to: CGPoint(x: 350, y: yPosition))
linepath.lineWidth = 8
let lineshape = CAShapeLayer()
lineshape.path = linepath.cgPath
lineshape.strokeColor = UIColor.blue.cgColor
lineshape.fillColor = UIColor.white.cgColor
self.view.layer.addSublayer(lineshape)
hourlabel.frame = CGRect(x: 5, y: yPosition - 20, width: 45, height: 40)
hourlabel.text = "\(n):00"
hourlabel.font = UIFont(name: "Avenir-Claro", size: 12)
hourlabel.textColor = UIColor.blue
hourlabel.textAlignment = .right
self.view.addSubview(hourlabel)
}
// ===== GESTURE =====
let gesto = UIPanGestureRecognizer()
gesto.addTarget(self, action: #selector(touchinput))
view.addGestureRecognizer(gesto)
}
}
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