LiveChart.swift

import UIKit
import Charts

var reading_a = [5,10,15,20,25,30]
var reading_b = [55,60,66,54,60,58]
var timer = Timer()

class LineChart2ViewController: DemoBaseViewController {

    @IBOutlet var chartView: LineChartView!
    @IBOutlet var sliderX: UISlider!
    @IBOutlet var sliderY: UISlider!
    @IBOutlet var sliderTextX: UITextField!
    @IBOutlet var sliderTextY: UITextField!
    
    override func viewDidLoad() {
        
        super.viewDidLoad()
        self.chartView.delegate = self
        let set_a = LineChartDataSet(entries:[ChartDataEntry(x: Double(0), y: Double(0))], label: "voice")
        set_a.drawCirclesEnabled = false
        set_a.setColor(UIColor.blue)
        self.chartView.data = LineChartData(dataSets: [set_a])
        timer = Timer.scheduledTimer(timeInterval: 0.9, target: self, selector: #selector(updateCounter), userInfo: nil, repeats: true)
    }

    var i = 1
    
    @objc func updateCounter() {
        self.chartView.data?.addEntry(ChartDataEntry(x: Double(i), y: Double(reading_a[i/4])), dataSetIndex: 0)
        self.chartView.setVisibleXRange(minXRange: Double(i), maxXRange: Double(i+1))
        self.chartView.notifyDataSetChanged()
        self.chartView.moveViewToX(Double(i))
        i = i + 1
    }
}