Summary:
When using the new .focused modifier to track focus within a large LazyVStack or LazyHStack, we observe a major frame-rate drop and stuttering on Apple TV (1st and 2nd generation).
Steps to Reproduce:
Create a LazyVStack (or LazyHStack) displaying a substantial list of data models (e.g., 100+ GroupData items).
Attach the .focused(::) modifier to each row, binding to an @FocusState variable of the same model type.
Build and run on an Apple TV device or simulator.
Scroll through the list using the remote.
static func == (lhs: GroupData, rhs: GroupData) -> Bool {
lhs.id == rhs.id
}
var id: String
var name: String
var subName: String
var subGroup: [GroupData] = []
var logo: URL?
}
struct TestView: View {
@FocusState var focusedGroup: GroupData?
let groupsArr: [GroupData]
var body: some View {
ScrollView {
LazyVStack {
ForEach(groupsArr, id: \.id) { group in
Button {
} label: {
GroupTestView(group: group)
}
.id(group.id)
.focused($focusedGroup, equals: group)
}
}
}
}
}
struct GroupTestView: View {
let group: GroupData
var body: some View {
HStack {
KFImage.url(group.logo)
.placeholder {
Image(systemName: "photo")
.opacity(0.2)
.imageScale(.large)
}
.resizable()
.scaledToFit()
.frame(width: 70)
VStack {
Text(group.name)
Text(group.subName)
}
}
}
}
Expected Behavior
Scrolling remains smooth (60 fps) regardless of list size.
Focus updates without introducing visible lag.
Observed Behavior
Frame rate drops significantly when .focused is applied.
Scrolling becomes visibly laggy, especially on older Apple TV hardware.
Even when binding an @FocusState<String?> (storing only the id), performance improves slightly but remains suboptimal.
Workarounds Tried
Switched to @FocusState of type String to track only the ID of each group, this has helped but there is still a big performance decrease.
Minimised view-body complexity and removed other modifiers.
Verified that excluding .focused entirely restores smooth scrolling.
Any guidance or suggestions would be greatly appreciated.
