UISlider with gradient background not working when used without storyboard - ios

Question

When I try create UISlider with gradient background programmatically, it is not working correctly (gradient is repeated many times). When I use the code below with storyboard, everything works fine. Am I missing something here? Thank you!
UISlider subclass
class GradientSlider: UISlider {
var thickness: CGFloat = 20 {
didSet {
setup()
}
}
var sliderThumbImage: UIImage? {
didSet {
setup()
}
}
func setup() {
let minTrackStartColor = UIColor.red
let minTrackEndColor = UIColor.yellow
let maxTrackColor = UIColor.green
do {
self.setMinimumTrackImage(try self.gradientImage(
size: self.trackRect(forBounds: self.bounds).size,
colorSet: [minTrackStartColor.cgColor, minTrackEndColor.cgColor]),
for: .normal)
self.setMaximumTrackImage(try self.gradientImage(
size: self.trackRect(forBounds: self.bounds).size,
colorSet: [maxTrackColor.cgColor, maxTrackColor.cgColor]),
for: .normal)
self.setThumbImage(sliderThumbImage, for: .normal)
} catch {
self.minimumTrackTintColor = minTrackStartColor
self.maximumTrackTintColor = maxTrackColor
}
print("SZ \(self.bounds.size)")
}
func gradientImage(size: CGSize, colorSet: [CGColor]) throws -> UIImage? {
let tgl = CAGradientLayer()
tgl.frame = CGRect.init(x:0, y:0, width:size.width, height: size.height)
tgl.cornerRadius = tgl.frame.height / 2
tgl.masksToBounds = false
tgl.colors = colorSet
tgl.startPoint = CGPoint.init(x:0.0, y:0.5)
tgl.endPoint = CGPoint.init(x:1.0, y:0.5)
UIGraphicsBeginImageContextWithOptions(size, tgl.isOpaque, 0.0);
guard let context = UIGraphicsGetCurrentContext() else { return nil }
tgl.render(in: context)
let image =
UIGraphicsGetImageFromCurrentImageContext()?.resizableImage(withCapInsets:
UIEdgeInsets.init(top: 0, left: size.height, bottom: 0, right: size.height))
UIGraphicsEndImageContext()
return image!
}
override func trackRect(forBounds bounds: CGRect) -> CGRect {
return CGRect(
x: bounds.origin.x,
y: bounds.origin.y,
width: bounds.width,
height: thickness
)
}
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setup()
}
}
Adding Slider Programmatically
func addSlider() {
var slider = GradientSlider()
slider.frame = CGRect(x: 30, y: 600, width: view.frame.width - 30, height: 20)
slider.isContinuous = true
slider.value = 0.5
slider.addTarget(self, action: #selector(slide(sender:)), for: .valueChanged)
view.addSubview(slider)
}
original answer

Answer 1

I replaced the addSlider code, and it worked for me.
func addSlider() {
let slider = GradientSlider.init(frame: CGRect(x: 30, y: 100, width: view.frame.width - 30, height: 20))
slider.isContinuous = true
slider.value = 0.5
slider.addTarget(self, action: #selector(slide(sender:)), for: .valueChanged)
view.addSubview(slider)
}