A quick study of making weird, custom UI components with SwiftUI

SliderView.swift

import SwiftUI

struct SliderView: View {
    
    @State var height: CGFloat = .infinity
    @State var sliderOpacity: Double = 0
    
    let action: (() -> Void)
    
    var slide: some Gesture {
        DragGesture(minimumDistance: 0, coordinateSpace: .local)
        .onChanged {
            self.height =  $0.location.y
            self.sliderOpacity = 1
            
            if self.height < 10 {
                self.action()
            }
        }
        .onEnded { _ in
            self.height = .infinity
            self.sliderOpacity = 0
        }
    }
    
    var decoration: some View {
        VStack(spacing: 0) {
            Rectangle()
                .fill(Color.black)
                .frame(height: 20)
            Rectangle()
                .fill(Color.yellow)
                .frame(height: 50)
            Rectangle()
                .fill(Color.black)
                .frame(height: 40)
        }.padding(.top, 300)
    }
    
    
    var body: some View {
        ZStack {
            Rectangle()
                .fill(Color(hue: (48 / 360), saturation: 1, brightness: 0.25))
            VStack {
                Spacer()
                    .frame(maxHeight: height)
                    .layoutPriority(1)
                Rectangle()
                    .fill(Color.yellow)
                    .opacity(sliderOpacity)
                    .animation(.easeInOut)
            }
            
            decoration
        }.frame(width: 100)
        .gesture(slide)
        .cornerRadius(40)
    }
}

struct SliderView_Previews: PreviewProvider {
    static var previews: some View {
        ZStack {
            Color.black
            .edgesIgnoringSafeArea(.all)
            SliderView(action: { print("Bam!")})
        }
    }
}