SwiftUI 如何使用滑动禁用行删除？

Question

我在 SwiftUI 中使用 Xcode 11.1。

我使用以下代码实现了列表删除和排序功能。

如何使用滑动禁用行删除？

import SwiftUI

struct ContentView: View {
    @State var fruits = ["Apple",  "Orange",  "Banana"]

    var body: some View {
        NavigationView {
            List {
                ForEach(fruits, id: \.self) { fruit in
                    Text(fruit)
                }
                .onMove(perform: move)
                .onDelete(perform: delete)
            }
            .navigationBarItems(trailing: EditButton())
        }
    }

    func delete(offsets: IndexSet) {
        fruits.remove(atOffsets: offsets)
    }

    func move(source: IndexSet, destination: Int) {
        fruits.move(fromOffsets: source, toOffset: destination)
    }
}

Answer 1

您可以使用.deleteDisabled(_ isDisabled:)修饰符。但是你必须考虑到这个修饰符的返回类型是View，不是Text。所以它实现起来有点复杂。您可以使用此示例：

1. 创建一个CellView这样的：

struct CellView: View {
    var title: String
    var isDeletable: Bool

    var body: some View {
        return Text(title).deleteDisabled(!isDeletable)
    }
}

您可以使用VStacks、HStacks 等来设计您的单元格，但您应该考虑在此层次结构的父级上使用此修饰符。如下图所示：

var body: some View {
    HStack {
        VStack {
            ZStack {
                ...
            }
        }
    }
    .deleteDisabled(!isDeletable)
}

2. 之后，您可以ForEach像下面这样使用它：

struct ContentView: View {
    @State var fruits = ["Apple",  "Orange",  "Banana"]

    var body: some View {
        NavigationView {
            List {
                ForEach(fruits, id: \.self) { fruit -> CellView in
                    if fruit == "Orange" {
                        return CellView(title: fruit, isDeletable: true)
                    } else {
                        return CellView(title: fruit, isDeletable: false)
                    }
                }
                .onMove(perform: move)
                .onDelete(perform: delete)
            }
            .navigationBarItems(trailing: EditButton())
        }
    }

    func delete(offsets: IndexSet) {
        fruits.remove(atOffsets: offsets)
    }

    func move(source: IndexSet, destination: Int) {
        fruits.move(fromOffsets: source, toOffset: destination)
    }
}