As of June 22nd this is included in the SwiftUI 2 beta. https://developer.apple.com/documentation/swiftui/scrollviewproxy

The Apple implementation uses just .id(_:) and I had update issues with that where Views with an id sometimes won't update when their ObservedObject changed. Maybe this has been fixed in the new SwiftUI 2 beta.

Also the Apple implementation only supports iOS 14 so I think this repo is still useful for backwards compatibility.

ScrollViewProxy

Adds ScrollViewReader and ScrollViewProxy that help you scroll to locations in a ScrollView

To get a ScrollViewProxy you can either use the conveinience init on ScrollView

ScrollView { proxy in
    ...
}

or add a ScrollViewReader to any View that creates a UIScrollView under the hood

List {
    ScrollViewReader { proxy in
        ...
    }
}

The ScrollViewProxy currently has two functions you can call

/// Scrolls to an edge or corner
public func scrollTo(_ alignment: Alignment, animated: Bool = true)

/// Scrolls the view with ID to an edge or corner
public func scrollTo(_ id: ID, alignment: Alignment = .top, animated: Bool = true)

To use the scroll to ID function you have to add an ID to the view you want to scroll to

ScrollView { proxy in
    HStack { ... }
        .scrollId("someId")
}

*This is the only part that is different from the SwiftUI 2.0 implementation because I don't know how to access Views by ID from the .id(_:) function

Example

Everything put together in an example

struct ScrollViewProxySimpleExample: View {
    
    @State var randomInt = Int.random(in: 0..<200)
    @State var proxy: ScrollViewProxy? = nil
    
    var body: some View {
        VStack {
            ScrollView { proxy in
                ForEach(0..<200) { index in
                    VStack {
                        Text("\(index)").font(.title)
                        Spacer()
                    }
                    .padding()
                    .scrollId(index)
                }.onAppear {
                    self.proxy = proxy
                }
            }
            HStack {
                Button(action: {
                    self.proxy?.scrollTo(self.randomInt, alignment: .center)
                    self.randomInt = Int.random(in: 0..<200)
                }, label: {
                    Text("Go to \(self.randomInt)")
                })
                Spacer()
                Button(action: { self.proxy?.scrollTo(.top) }, label: {
                    Text("Top")
                })
                Spacer()
                Button(action: { self.proxy?.scrollTo(.center) }, label: {
                    Text("Center")
                })
                Spacer()
                Button(action: { self.proxy?.scrollTo(.bottom) }, label: {
                    Text("Bottom")
                })
            }
        }
    }
}

Deintegrate

Want to drop iOS 13 support and move to the SwiftUI 2.0 version?

Remove the Package
Add this extension:

extension View {
    public func scrollId<ID: Hashable>(_ id: ID) -> some View {
        id(id)
    } 
}

(Or replace all .scrollId with .id)

mumer92 / scrollviewproxy Goto Github PK