How can I scrollToTop in SwiftUI

Question

I am learning SwiftUI, but I have a problem... How can I scroll to top in ScrollView when the SegmentedControl value changed?

This is code for the main view to show Data:

var body: some View {
    NavigationView {
        SegmentedControl(selection: $selected) {
            Text("Food").tag(0)
            Text("Drinks").tag(1)
            Text("Wines").tag(2)
            }
            .padding()
        ScrollView {
            VStack(alignment: .center) {
                if selected == 0 {
                    ForEach (persons) {
                        AnyCell(person: $0, animal: nil, wine: nil)
                    }
                } else if selected == 1 {
                    ForEach (animals) {
                        AnyCell(person: nil, animal: $0, wine: nil)
                    }
                } else {
                    ForEach (wines) {
                        AnyCell(person: nil, animal: nil, wine: $0)
                    }
                }
            }
            }
            .navigationBarTitle(Text("Food list"), displayMode: .inline)
    }
}

Thank you

user_1059895 · Answer

In SwiftUI, if you change the value of a variable, any of the body properties that depend on it will be recomputed. In your case, just changing the selection will completely reset the ScrollView.

I had to fill in a bunch of missing pieces (please include ALL of the relevant code in the future), but here's what I have:

import SwiftUI

let people = ["John", "Sarah", "Cathy"]
let animals = ["Cat", "Dog", "Rabbit", "Bird", "Lion", "Snake", "Cat", "Dog", "Rabbit", "Bird", "Lion", "Snake"]
let wines = ["Sauvignon Blanc", "Syrah", "Pinot Noir", "Champagne", "Sauvignon Blanc", "Syrah", "Pinot Noir", "Champagne", "Sauvignon Blanc", "Syrah", "Pinot Noir", "Champagne", "Sauvignon Blanc", "Syrah", "Pinot Noir", "Champagne"]

struct ContentView : View {
    @State var selected: Int = 0

    var body: some View {
        NavigationView {
            VStack {
                SegmentedControl(selection: $selected) {
                    Text("Food").tag(0)
                    Text("Drinks").tag(1)
                    Text("Wines").tag(2)
                    }
                    .padding()

                    if selected == 0 {
                        ScrollView {
                            VStack(alignment: .center) {
                                ForEach (people.identified(by: \.self)) {
                                    CellView(title: $0)
                                }
                            }
                        }
                    } else if selected == 1 {
                        ScrollView {
                            VStack(alignment: .center) {
                                ForEach (animals.identified(by: \.self)) {
                                    CellView(title: $0)
                                }
                            }
                        }
                    } else {
                        ScrollView {
                            VStack(alignment: .center) {
                                ForEach (wines.identified(by: \.self)) {
                                    CellView(title: $0)
                                }
                            }
                        }
                    }
                }.navigationBarTitle(Text("Food list"), displayMode: .inline)
        }
    }
}

struct CellView : View {
    let title: String

    var body: some View {
        Text(title).font(.largeTitle).frame(height: 100).background(Color.green)
    }
}

When you change selected, the ScrollView will be recreated, which will leave its scroller at the top. To test it out, tap "Wines", scroll down a bit, and then tap either of the others.

How can I scrollToTop in SwiftUI

1 Answers