How do I display an Array of Arrays in swiftUI

Question

In a meal planning app a user selects items they need for each day of the week which creates an array of items for each day. The arrays are then inserted into a shopping list array creating an Array of Arrays with all the items.

I'm stuck trying to show the combined list. In my code I am returning the count of arrays correctly, however when I try to display the items in each array I'm failing. Any help would be appreciated!

Here is a simplified example of what I'm trying to do:

import SwiftUI

struct ShoppingListView: View {
    
    var shoppingList: Array<Array<String>>

    
    var body: some View {
        VStack(alignment: .leading) {
            ForEach(0..<shoppingList.count, id: \.self) {list in
                Text("number of arrays")
                VStack {
                    List(0..<list) { item in
                        Text("item = \(item)")
                    }
                }
            }
        }
    }
}

struct ShoppingListView_Previews: PreviewProvider {
    static var previews: some View {
        let list = [["eggs", "bread", "milk", "cheese" ],["steak", "potatoes", "salad kit"]]
        ShoppingListView(shoppingList: list)
    }
}

Phil Dukhov · Accepted Answer · 2021-08-22 08:50:54Z

6

First of all, newer use 0..<shoppingList.count inside ForEach or List, because the day you'll change items count you'll face an issue with your list not updating, like in this this case. Use shoppingList.indices instead.

You're enumerating indexes, but looks like you're expecting to get an item in the block. It's not gonna happen.

Perfectly create a struct for your items and conform it to Identifiable, then you'll be able to call ForEach(shoppingList) { and get your item in the block.

Until then you can use enumerating indices without problems, just get your item by index from the list:

var shoppingList: Array<Array<String>> = [["eggs", "bread", "milk", "cheese" ],["steak", "potatoes", "salad kit"]]

var body: some View {
    VStack(alignment: .leading) {
        ForEach(shoppingList.indices, id: \.self) { i in
            Text("number of arrays")
            let sublist = shoppingList[i]
            VStack {
                List(sublist.indices, id: \.self) { j in
                    Text("item = \(sublist[j])")
                }
            }
        }
    }
}

answered Aug 22, 2021 at 8:50

Phil Dukhov

91k22 gold badges276 silver badges302 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

swiftPunk Over a year ago

@TJMac: The right way of defining the thing you want is Array<Array<String>>

George Over a year ago

Basing things off indices isn't great when the data changes, because something that used to be bread for example is now in the row where eggs is. Can cause those unstable identifier warnings and cause strange animations. I think doing the ID from the name like @workingdog is a more reliable method. But yeah, indices is better because things like ArraySlice don't always start at index 0. Ideally, the items in this shopping list would be their own struct that, for as long as they live, each item has their own unique and constant ID.

workingdog support Ukraine · Accepted Answer · 2021-08-22 08:56:53Z

2

you could just do this:

struct ShoppingListView: View {

var shoppingList: [[String]] = [["1","2","3"], ["4","5","6"], ["7","8"]]

var body: some View {
    VStack(alignment: .leading) {
        Text("number of arrays is \(shoppingList.count)")
        ForEach(shoppingList, id: \.self) { list in
            VStack {
                List(list, id: \.self) { item in
                    Text("item = \(item)")
                }
            }
        }
    }
}
}

answered Aug 22, 2021 at 8:56

workingdog support Ukraine

38.9k5 gold badges47 silver badges52 bronze badges

2 Comments

TJMac Over a year ago

I'm not sure where I went wrong in my prior attempts, but I thought I had attempted this before without success. With your response I went back and now it's working fine. Thank you for the help, this is the solution I ended up going with.

Oliver Pearmain Over a year ago

Thanks. For me it was the inclusion of the id parameter on the ForEach that I'd missed.

Collectives™ on Stack Overflow

How do I display an Array of Arrays in swiftUI

2 Answers 2

2 Comments

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related