Hi guys. Can someone please confirm this bug so I report it? The issue is that SwiftData relationships don't update the views in some specific situations on devices running iOS 18 Beta. One clear example is with CloudKit. I created a small example for testing. The following code creates two @models, one to store bands and another to store their records. The following code works with no issues. (You need to connect to a CloudKit container and test it on two devices)
import SwiftUI
import SwiftData
struct ContentView: View {
@Environment(\.modelContext) private var modelContext
@Query private var records: [Record]
var body: some View {
NavigationStack {
List(records) { record in
VStack(alignment: .leading) {
Text(record.title)
Text(record.band?.name ?? "Undefined")
}
}
.toolbar {
ToolbarItem {
Button("Add Record") {
let randomNumber = Int.random(in: 1...100)
let newBand = Band(name: "New Band \(randomNumber)", records: nil)
modelContext.insert(newBand)
let newRecord = Record(title: "New Record \(randomNumber)", band: newBand)
modelContext.insert(newRecord)
}
}
}
}
}
}
@Model
final class Record {
var title: String = ""
var band: Band?
init(title: String, band: Band?) {
self.title = title
self.band = band
}
}
@Model
final class Band {
var name: String = ""
var records: [Record]?
init(name: String, records: [Record]?) {
self.name = name
self.records = records
}
}
This view includes a button at the top to add a new record associated with a new band. The data appears on both devices, but if you include more views inside the List, the views on the second device are not updated to show the values of the relationships. For example, if you extract the row to a separate view, the second device shows the relationships as "Undefined". You can try the following code.
struct ContentView: View {
@Environment(\.modelContext) private var modelContext
@Query private var records: [Record]
var body: some View {
NavigationStack {
List {
ForEach(records) { record in
RecordRow(record: record)
}
}
.toolbar {
ToolbarItem {
Button("Add Record") {
let randomNumber = Int.random(in: 1...100)
let newBand = Band(name: "New Band \(randomNumber)", records: nil)
modelContext.insert(newBand)
let newRecord = Record(title: "New Record \(randomNumber)", band: newBand)
modelContext.insert(newRecord)
}
}
}
}
}
}
struct RecordRow: View {
let record: Record
var body: some View {
VStack(alignment: .leading) {
Text(record.title)
Text(record.band?.name ?? "Undefined")
}
}
}
Here I use a ForEach loop and move the row to a separate view. Now on the second device the relationships are nil, so the row shows the text "Undefined" instead of the name of the band.
I attached an image from my iPad. I inserted all the information on my iPhone. The first three rows were inserted with the first view. But the last two rows were inserted after I extracted the rows to a separate view. Here you can see that the relationships are nil and therefore shown as "Undefined". The views are not updated to show the real value of the relationship.
This example shows the issue with CloudKit, but this also happens locally in some situations. The system doesn't detect updates in relationships and therefore doesn't refresh the views.
Please, let me know if you can reproduce the issue. I'm using Mac Sequoia 15.1, and two devices with iOS 18.0.
