Please check this :
let ds1 = LineChartDataSet(values: yse1, label: "Hello")
ds1.colors = [NSUIColor.red]
ds1.drawCirclesEnabled = false
ds1.drawValuesEnabled = false
ds1.mode = .cubicBezier // add this line
data.addDataSet(ds1)
let ds2 = LineChartDataSet(values: yse2, label: "World")
ds2.colors = [NSUIColor.blue]
ds2.drawCirclesEnabled = false
ds2.drawValuesEnabled = false
ds2.mode = .cubicBezier // add this line
data.addDataSet(ds2)
solved iOS Charts, wavy lines