CODEWITHSUNDEEP
swiftuilabeluislider
CheeseFerrari
CheeseFerrari

Reputation: 57

Updating UILabel with UISlider throwing "unresolved identifier" error for Sender call

The code below is the only code I am using. I have programmatically built a UISlider with a label that I want to update. I've written a function that should call the sender of the UISlider and update the label field to the value of the slider. But it keeps throwing the "unresolved identifier" error for the variable name of the label. Where do I place the function so it can access the label value? I've tried everything.

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad()
    {
        super.viewDidLoad()
        let mySlider = UISlider(frame:CGRect(x: 60, y:550, width: 300, height: 20))
        mySlider.minimumValue = 5
        mySlider.maximumValue = 60
        mySlider.isContinuous = true
        mySlider.tintColor = .white
        mySlider.addTarget(self, action: #selector(ViewController.sliderValueDidChange(_:)), for: .valueChanged)

        let minuteLabel = UILabel(frame: CGRect(1500, 2000, 150, 1200))
        minuteLabel.center = CGPoint(200, 350)
        minuteLabel.textAlignment = .center
        minuteLabel.font = UIFont(name: minuteLabel.font.fontName, size:250)
        mySlider.addTarget(self, action: #selector(ViewController.sliderValueDidChange(_:)),for: .valueChanged)
        minuteLabel.textColor = UIColor.white
        minuteLabel.text = "\(mySlider.value)"

        self.view.addSubview(minuteLabel)
        self.view.addSubview(mySlider)
    }

    public func sliderValueDidChange(_sender: UISlider) {
        minuteLabel.text = "\(_sender.value)"
    }
}

Upvotes: 1

Views: 86

Answers (1)

Ivan Smetanin
Ivan Smetanin

Reputation: 2039

It's because you create minuteLabel in viewDidLoad() but not assigning to any property inside your ViewController.

You can just create property minuteLabel inside class and assign your minuteLabel from viewDidLoad() to this.

class ViewController: UIViewController {

    private var minuteLabel: UILabel?

    override func viewDidLoad()
    {
        super.viewDidLoad()
        let mySlider = UISlider(frame:CGRect(x: 60, y:550, width: 300, height: 20))
        mySlider.minimumValue = 5
        mySlider.maximumValue = 60
        mySlider.isContinuous = true
        mySlider.tintColor = .white
        mySlider.addTarget(self, action: #selector(ViewController.sliderValueDidChange(_:)), for: .valueChanged)

        let minuteLabel = UILabel(frame: CGRect(1500, 2000, 150, 1200))
        minuteLabel.center = CGPoint(200, 350)
        minuteLabel.textAlignment = .center
        minuteLabel.font = UIFont(name: minuteLabel.font.fontName, size:250)
        mySlider.addTarget(self, action: #selector(ViewController.sliderValueDidChange(_:)),for: .valueChanged)
        minuteLabel.textColor = UIColor.white
        minuteLabel.text = "\(mySlider.value)"

        self.view.addSubview(minuteLabel)
        self.view.addSubview(mySlider)

        self.minuteLabel = minuteLabel // assign to class property
    }

    public func sliderValueDidChange(_sender: UISlider) {
        minuteLabel?.text = "\(_sender.value)"
    }

}

Upvotes: 1

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