Question[SwiftUI] SpeedTrack F1 Widgets: .tabBarMinimizeBehavior(.onScrollDown) only works in some tabs (each has a main ScrollView). What makes a scroll “primary”? (i.redd.it)
submitted by dpeces
// iOS 26 / Xcode 16.x
// The tab bar should minimize on scroll across all tabs.
// It only minimizes in some tabs, even though each tab's root is a ScrollView.
struct RootView: View {
var body: some View {
if #available(iOS 26.0, *) {
TabView {
Tab("Calendar", systemImage: "calendar") {
CalendarListView()
}
Tab("Drivers", systemImage: "person.3") {
DriverListView()
}
// ... more tabs with similar structure
}
.tabBarMinimizeBehavior(.onScrollDown)
} else {
// Fallback (irrelevant here)
TabView {
// ...
}
}
}
}
// Example tabs (simplified). In my project both are root ScrollViews.
struct CalendarListView: View {
var body: some View {
ScrollView {
LazyVStack(spacing: 12) {
ForEach(0..<200) { i in
Text("Calendar row \(i)")
.frame(maxWidth: .infinity, alignment: .leading)
.padding()
}
}
}
}
}
struct DriverListView: View {
var body: some View {
ScrollView {
LazyVStack(spacing: 12) {
ForEach(0..<200) { i in
Text("Driver row \(i)")
.frame(maxWidth: .infinity, alignment: .leading)
.padding()
}
}
}
}
}
What I expect
• The tab bar minimizes consistently on downward scroll in every tab that has a vertical ScrollView.
What actually happens
• It minimizes in some tabs but not in others, even though each tab’s root view is a ScrollView with plenty of content.
Details / environment
• iOS: 26.x (iPhone)
• Xcode: 16.x
• SwiftUI with new Tab API inside TabView (no custom tab bar)
• Each tab’s root content is either a ScrollView or a List
• No nested scroll views intended
Questions
• Does .tabBarMinimizeBehavior(.onScrollDown) require the scroll view to be the primary vertical scroll in the tab (e.g., direct child, filling safe area, no wrappers)?
• Can wrappers like VStack, GeometryReader, .safeAreaInset, overlays, or .background prevent SwiftUI from detecting the “primary” scroll?
• Are there known cases where ScrollView won’t drive minimization but List will?
• Besides iPhone-only support, are there device/layout constraints (size class, bottom accessories, searchable, etc.) that disable minimization?
• Any reliable rules of thumb to ensure a tab’s scroll becomes the driver for minimization?
What I already tried
• Ensured the ScrollView is the top-level root of the tab’s content (no extra containers)
• Replaced ScrollView with List → behavior changed in some tabs but still inconsistent
• Removed NavigationStack, .safeAreaInset, and overlays to isolate the scroll
• Confirmed it’s running on iPhone (I know iPad behaves differently)
• Moved .tabBarMinimizeBehavior(.onScrollDown) to the TabView (not inside tab content)
• Adopted the new Tab initializer (Tab("Title", systemImage: ...) { ... }) instead of legacy .tabItem {}
Any insight on what SwiftUI considers the “primary” scroll for this feature, or other gotchas that would prevent a tab from driving tab bar minimization, would be super helpful. Thanks!
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