Simple SwiftUI onScroll Workaround

OnScrollModifier.swift

extension View {
    func onScroll(_ isScrolling: Binding<Bool>) -> some View {
        modifier(OnScrollModifier(isScrolling: isScrolling))
    }
}

private struct OnScrollModifier: ViewModifier {
    @State private var callbackID = 0
    @Binding var isScrolling: Bool

    func body(content: Content) -> some View {
        content
            .onAppear {
                let callbackID = nextCallbackID()
                listenForScrollStart(callbackID)
                listenForScrollEnd(callbackID)
            }
            .onDisappear {
                nextCallbackID()
            }
    }

    private func listenForScrollStart(_ callbackID: Int? = nil) {
        let callbackID = callbackID ?? nextCallbackID()
        RunLoop.main.perform(inModes: [.tracking]) {
            guard callbackID == self.callbackID else {
                return
            }

            isScrolling = true
            listenForScrollEnd()
        }
    }

    private func listenForScrollEnd(_ callbackID: Int? = nil) {
        let callbackID = callbackID ?? nextCallbackID()
        RunLoop.main.perform { // Main runloop doesn't fire while user is scrolling
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
                guard callbackID == self.callbackID else {
                    return
                }

                isScrolling = false
                listenForScrollStart()
            }
        }
    }

    @discardableResult
    private func nextCallbackID() -> Int {
        callbackID += 1
        return callbackID
    }
}