ios – How you can know if the primary merchandise within the listing that’s inside a ForEach loop is seen in SwiftUI?

You need to use enumerated() together with ForEach to trace an index of the array and use it to cover and present your button. One thing like this.

struct ContentView: View {
    
    let gadgets = (1...50).map(String.init)
    @State non-public var showScrollButton = false
   
    var physique: some View {
        ScrollViewReader { reader in
            ZStack(alignment: .bottomTrailing) {
                Record {
                    let enumerated = gadgets.enumerated().map({ $0 })
                    ForEach(enumerated, id: .factor) { (index, merchandise) in
                        Textual content(merchandise)
                            .id(index)
                            .onAppear {
                                guard index == 0, showScrollButton else {
                                    return
                                }
                                showScrollButton = false
                            }
                            .onDisappear {
                                guard index == 0, !showScrollButton else {
                                    return
                                }
                                showScrollButton = true
                            }
                    }
                }
                if showScrollButton {
                    Button(motion: {
                        withAnimation {
                            reader.scrollTo(0, anchor: .prime)
                        }
                    }, label: {
                        Picture(systemName: "chevron.up.circle")
                            .font(.largeTitle)
                            .foregroundColor(.black)
                            .padding()
                            .padding(.trailing)
                    })
                }
            }
        }
    }
}