Swift 如何获取嵌套数组中项的路径以修改数组

如果我没记错的话，你要找的是key paths美元.它们表示获取/设置类型的属性的"路径"，或数组的索引.

键路径将表示您要追加到的array.在每次递归调用中，您都会一直附加到它后面，以"深入一层".最初，它是\.self，代表一条"空"路径.

private func populateNestedData(items: [Item], keyPath: WritableKeyPath<[ItemEntry], [ItemEntry]> = \.self) {
    for item in items {
        // itemEntries[keyPath: \.self] is the same as itemEntries
        // so you can get rid of the itemsAreNested parameter
        itemEntries[keyPath: keyPath].append(createItemEntry(item: item))
        
        if (!item.childrenArray.isEmpty) {
            let children = ...
            // this is the index of the last item inserted into itemEntries[keyPath: keyPath]
            let lastInsertedIndex = itemEntries[keyPath: keyPath].count - 1
            populateNestedData(
                items: children,
                // appends the key path representing the children of the item last inserted to itemEntries[keyPath: keyPath]
                keyPath: keyPath.appending(path: \.[lastInsertedIndex].children)
            )
        }
    }
}

也就是说，我认为最好将其编写为返回[ItemEntry]的函数:

private func populateNestedData(items: [Item]) -> [ItemEntry] {
    var entries = [ItemEntry]()
    for item in items {
        var itemEntry = createItemEntry(item: item)
        
        if (!item.childrenArray.isEmpty) {
            let children = ...
            itemEntry.children = populateNestedData(items: children)
        }
        entries.append(itemEntry)
    }
    return entries
}

当您想要调用此命令时，并将其分配给itemEntries状态:

itemEntries = populateNestedData(items: ...)