Updated for Xcode 12.0
Updated in iOS 14
SwiftUI’s List
has an enhanced initializer that lets us create expanding sections with child elements – they will be rendered with tappable arrows that open out to reveal children when tapped.
To use this form of List
you need to have data in a precise form: your data model should have an optional array of children that are of the same type, so you can create a tree.
Normally you’re likely to load this kind of stuff from JSON or similar, but to keep things simple I’ll just paste in some hard-coded data so you can see what it ought to look like:
struct Bookmark: Identifiable {
let id = UUID()
let name: String
let icon: String
var items: [Bookmark]?
// some example websites
static let apple = Bookmark(name: "Apple", icon: "1.circle")
static let bbc = Bookmark(name: "BBC", icon: "square.and.pencil")
static let swift = Bookmark(name: "Swift", icon: "bolt.fill")
static let twitter = Bookmark(name: "Twitter", icon: "mic")
// some example groups
static let example1 = Bookmark(name: "Favorites", icon: "star", items: [Bookmark.apple, Bookmark.bbc, Bookmark.swift, Bookmark.twitter])
static let example2 = Bookmark(name: "Recent", icon: "timer", items: [Bookmark.apple, Bookmark.bbc, Bookmark.swift, Bookmark.twitter])
static let example3 = Bookmark(name: "Recommended", icon: "hand.thumbsup", items: [Bookmark.apple, Bookmark.bbc, Bookmark.swift, Bookmark.twitter])
}
That’s just placeholder data so I’ve repeated the same bookmarks several times, but hopefully you get the point.
Once you have your data in place, you can load it into a list by passing in your array of data plus a keypath to where the children are, which in our case would be \.items
. You’ll then get a regular closure where you can provide your row data, just like normal.
So, you can try it out like this:
struct ContentView: View {
let items: [Bookmark] = [.example1, .example2, .example3]
var body: some View {
List(items, children: \.items) { row in
Image(systemName: row.icon)
Text(row.name)
}
}
}
When that runs you’ll see three rows for our groups, plus disclosure indicators that fold out to reveal their children.
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