Gradient Fill in Swift for iOS-Charts

This works perfectly (Swift 3.1 and ios-charts 3.0.1)

---

let gradientColors = [UIColor.cyan.cgColor, UIColor.clear.cgColor] as CFArray // Colors of the gradient
let colorLocations:[CGFloat] = [1.0, 0.0] // Positioning of the gradient
let gradient = CGGradient.init(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: gradientColors, locations: colorLocations) // Gradient Object
yourDataSetName.fill = Fill.fillWithLinearGradient(gradient!, angle: 90.0) // Set the Gradient
set.drawFilledEnabled = true // Draw the Gradient

Result

For swift4

let colorTop =  UIColor(red: 255.0/255.0, green: 149.0/255.0, blue: 0.0/255.0, alpha: 1.0).cgColor
let colorBottom = UIColor(red: 255.0/255.0, green: 94.0/255.0, blue: 58.0/255.0, alpha: 1.0).cgColor

let gradientColors = [colorTop, colorBottom] as CFArray
let colorLocations:[CGFloat] = [0.0, 1.0]
let gradient = CGGradient.init(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: gradientColors, locations: colorLocations) // Gradient Object
yourDataSetName.fill = Fill.fillWithLinearGradient(gradient!, angle: 90.0)

For Swift 5 use the following:

yourDataSetName.fill = LinearGradientFill(....
or
yourDataSetName.fill = ColorFill(...

More details you can read here: Charts

I believe this is the code that you are looking for. You should be able to use the same ChartFill class in Swift to set set1.fill.

let gradColors = [UIColor.cyanColor().CGColor, UIColor.clearColor.CGColor]
let colorLocations:[CGFloat] = [0.0, 1.0]
if let gradient = CGGradientCreateWithColors(CGColorSpaceCreateDeviceRGB(), gradColors, colorLocations) {
    set1.fill = ChartFill(linearGradient: gradient, angle: 90.0)
}