struct CircularProgressView: View {
    @State var progressValue: Float = 0.0
    @State private var isLoaderVisible: Bool = false
    var degree = 90

    var body: some View {
        ZStack {

                ProgressBar(progress: self.$progressValue)
                    .frame(width: 150.0, height: 150.0)
                    .padding(40.0)

        }.overlay(LoaderView(showLoader: isLoaderVisible))
            .onAppear {
                isLoaderVisible.toggle()
            }

    }

}
struct ProgressBar: View {
    @Binding var progress: Float
     @State var degree:Double = 90
    var body: some View {
        ZStack {
            Circle()
                .stroke(lineWidth: 20.0)
                .foregroundColor(Color.green)
        }
    }
}
struct CircularProgressView_Previews: PreviewProvider {
    static var previews: some View {
        CircularProgressView()
    }
}

//LoaderView的枚举

public enum LoaderAnimation {
    case low, medium, high

    var animationSpeed: Double {
        switch self {
            case .low: return 1.0
            case .medium: return 0.8
            case .high: return 10.2
        }
    }
}

这是我们在叠加和动画上设置的LoaderView

public struct LoaderView: View {

    var loaderAnimationSpeed: LoaderAnimation? = .high
    var showLoader: Bool = false

    public var body: some View {
        GeometryReader { reader in
            ZStack {
                Circle()
                    .stroke(lineWidth: 20.0)
                    .opacity(0.3)
                    .foregroundColor(Color.yellow)

                Circle()
                    .trim(from: 0.6, to: 1)
                    .stroke(.green, lineWidth: 20)
                    .rotationEffect(.degrees(showLoader ? 360 : 0))
                    .animation(Animation.easeInOut(duration: showLoader ? loaderAnimationSpeed?.animationSpeed ?? 0.0 : 1).repeatForever(autoreverses: false), value: showLoader)
            }
        }
    }

    public init( loaderAnimationSpeed: LoaderAnimation? = .medium, showLoader: Bool) {
        self.loaderAnimationSpeed = loaderAnimationSpeed
        self.showLoader = showLoader
    }
}