How to let users move rows in a list
Updated for Xcode 12.0
SwiftUI gives us simple hooks into lists to let us move rows around by attaching an onMove(perform:) modifier to items in a list, and have it call a method of our choosing when a move operation happens. That method needs to accept a source IndexSet and a destination Int, like this:
func move(from source: IndexSet, to destination: Int) {When moving several items it’s always a good idea to move the later ones first so that you avoid moving other items and getting your indexes confused. Fortunately, Swift’s sequences have a built-in way to move index sets for us, so we can just pass the parameters along and have it work correctly.
As an example, we could create a ContentView struct that sets up an array of three username strings, and asks SwiftUI to move them around calling a move() method. In order to activate moving – i.e., to make the drag handles appear – it also adds an edit button to the navigation view so the user can toggle editing mode.
Here’s the code:
struct ContentView: View {
@State private var users = ["Paul", "Taylor", "Adele"]
var body: some View {
NavigationView {
List {
ForEach(users, id: \.self) { user in
Text(user)
}
.onMove(perform: move)
}
.navigationBarItems(trailing: EditButton())
}
}
func move(from source: IndexSet, to destination: Int) {
users.move(fromOffsets: source, toOffset: destination)
}
}
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