In SwiftUI, where are the control events, i.e. scrollViewDidScroll to detect the bottom of list data

Question

In SwiftUI, does anyone know where are the control events such as scrollViewDidScroll to detect when a user reaches the bottom of a list causing an event to retrieve additio

Answer 1

In case you need more precise info on how for the scrollView or list has been scrolled, you could use the following extension as a workaround:

extension View {

    func onFrameChange(_ frameHandler: @escaping (CGRect)->(), 
                    enabled isEnabled: Bool = true) -> some View {

        guard isEnabled else { return AnyView(self) }

        return AnyView(self.background(GeometryReader { (geometry: GeometryProxy) in

            Color.clear.beforeReturn {

                frameHandler(geometry.frame(in: .global))
            }
        }))
    }

    private func beforeReturn(_ onBeforeReturn: ()->()) -> Self {
        onBeforeReturn()
        return self
    }
}

The way you can leverage the changed frame like this:

struct ContentView: View {

    var body: some View {

        ScrollView {

            ForEach(0..<100) { number in

                Text("\(number)").onFrameChange({ (frame) in

                    print("Origin is now \(frame.origin)")

                }, enabled: number == 0)
            }
        }
    }
}

The onFrameChange closure will be called while scrolling. Using a different color than clear might result in better performance.

edit: I've improved the code a little bit by getting the frame outside of the beforeReturn closure. This helps in the cases where the geometryProxy is not available within that closure.