swift - How customise Slider blue line in SwiftUI?

Question

Like in UISlider

let slider = UISlider()

slider.minimumTrackTintColor = .red

Answer 1

As pointed out in other answers you have limited ability to customize a Slider in SwiftUI. You can change the .accentColor(.red) but that only changes the minimumTrackTintColor.

Example of a Slider with .accentColor(.red)

Additionally, you can't change other things like thumbTintColor. If you want more customization than just minimumTrackTintColor that you have no choice but to use a UISlider in SwiftUI as rob mayoff stated.

Here is some code on how you can use a UISlider in SwiftUI

struct SwiftUISlider: UIViewRepresentable {

  final class Coordinator: NSObject {
    // The class property value is a binding: It’s a reference to the SwiftUISlider
    // value, which receives a reference to a @State variable value in ContentView.
    var value: Binding<Double>

    // Create the binding when you initialize the Coordinator
    init(value: Binding<Double>) {
      self.value = value
    }

    // Create a valueChanged(_:) action
    @objc func valueChanged(_ sender: UISlider) {
      self.value.wrappedValue = Double(sender.value)
    }
  }

  var thumbColor: UIColor = .white
  var minTrackColor: UIColor?
  var maxTrackColor: UIColor?

  @Binding var value: Double

  func makeUIView(context: Context) -> UISlider {
    let slider = UISlider(frame: .zero)
    slider.thumbTintColor = thumbColor
    slider.minimumTrackTintColor = minTrackColor
    slider.maximumTrackTintColor = maxTrackColor
    slider.value = Float(value)

    slider.addTarget(
      context.coordinator,
      action: #selector(Coordinator.valueChanged(_:)),
      for: .valueChanged
    )

    return slider
  }

  func updateUIView(_ uiView: UISlider, context: Context) {
    // Coordinating data between UIView and SwiftUI view
    uiView.value = Float(self.value)
  }

  func makeCoordinator() -> SwiftUISlider.Coordinator {
    Coordinator(value: $value)
  }
}

#if DEBUG
struct SwiftUISlider_Previews: PreviewProvider {
  static var previews: some View {
    SwiftUISlider(
      thumbColor: .white,
      minTrackColor: .blue,
      maxTrackColor: .green,
      value: .constant(0.5)
    )
  }
}
#endif

Then you can use this slider in your ContentView like this:

struct ContentView: View {
  @State var sliderValue: Double = 0.5

  var body: some View {
    VStack {
      Text("SliderValue: (sliderValue)")
      // Slider(value: $sliderValue).accentColor(.red).padding(.horizontal)

      SwiftUISlider(
        thumbColor: .green,
        minTrackColor: .red,
        maxTrackColor: .blue,
        value: $sliderValue
      ).padding(.horizontal)
    }
  }
}

Example:

Link to full project