如何在使用 CoreData 和 @FetchRequest 时对 SwiftUI 列表顺序更改进行动画处理

Question

我有一个从

@FetchRequest

检索到的 CoreData 对象列表。我希望根据对象的属性对列表进行重新排序；一个

Bool

。

在下面的代码中，当您单击行项目时，视图会重建并且顺序会更改，但这种情况会立即发生，并且没有动画，尽管在获取请求上有动画。

我也尝试过向

List

和

RowView

添加动画，但这也不起作用。

import SwiftUI

struct RowView: View {
    @ObservedObject var place: Place

    var body: some View {
        Button {
            place.visit()
            try? DataController.shared.container.viewContext.save()
        } label: {
            HStack {
                Text(place.wrappedName)
                Spacer()
                place.visited ? Image(systemName: "checkmark.circle.fill") : Image(systemName: "checkmark.circle")
            }
        }
    }
}

struct ListDetailView: View {
    let list: PlaceList

    @FetchRequest var places: FetchedResults<Place>

    init(list: PlaceList) {
        self.list = list
        _places = .init(
            entity: Place.entity(),
            sortDescriptors: [NSSortDescriptor(keyPath: \Place.visited, ascending: true)],
            predicate: NSPredicate(format: "list = %@", list),
            animation: .default
        )
    }

    var body: some View {
        VStack {
            Text(self.list.wrappedName)
                .font(.headline)
            List {
                ForEach(places) { place in
                    RowView(place: place)
                }
            }
            .listStyle(.plain)
        }
    }
}

Answer 1

你需要一个动画块，例如

withAnimation {
    place.visit()
    // save if you like
}

Answer 2

struct ListDetailView: View {
let list: PlaceList

@FetchRequest var places: FetchedResults<Place>

init(list: PlaceList) {
    self.list = list
    _places = .init(
        entity: Place.entity(),
        sortDescriptors: [NSSortDescriptor(keyPath: \Place.visited, ascending: true)],
        predicate: NSPredicate(format: "list = %@", list),
        animation: .default
    )
}

var body: some View {
    VStack {
        Text(self.list.wrappedName)
            .font(.headline)
        List {
            ForEach(places) { place in
                RowView(place: place)
                    .animation(.default) // Add animation modifier here
            }
        }
        .listStyle(.plain)
    }
}

}