# Split views and columns
## Intent
Provide a lightweight, customizable multi-column layout for iPad/macOS without relying on `NavigationSplitView`.
## Custom split column pattern (manual HStack)
Use this when you want full control over column sizing, behavior, and environment tweaks.
```swift
@MainActor
struct AppView: View {
@Environment(\.horizontalSizeClass) private var horizontalSizeClass
@AppStorage("showSecondaryColumn") private var showSecondaryColumn = true
var body: some View {
HStack(spacing: 0) {
primaryColumn
if shouldShowSecondaryColumn {
Divider().edgesIgnoringSafeArea(.all)
secondaryColumn
}
}
}
private var shouldShowSecondaryColumn: Bool {
horizontalSizeClass == .regular
&& showSecondaryColumn
}
private var primaryColumn: some View {
TabView { /* tabs */ }
}
private var secondaryColumn: some View {
NotificationsTab()
.environment(\.isSecondaryColumn, true)
.frame(maxWidth: .secondaryColumnWidth)
}
}
```
## Notes on the custom approach
- Use a shared preference or setting to toggle the secondary column.
- Inject an environment flag (e.g., `isSecondaryColumn`) so child views can adapt behavior.
- Prefer a fixed or capped width for the secondary column to avoid layout thrash.
## Alternative: NavigationSplitView
`NavigationSplitView` can handle sidebar + detail + supplementary columns for you, but is harder to customize in cases like:\n- a dedicated notification column independent of selection,\n- custom sizing, or\n- different toolbar behaviors per column.
```swift
@MainActor
struct AppView: View {
var body: some View {
NavigationSplitView {
SidebarView()
} content: {
MainContentView()
} detail: {
NotificationsView()
}
}
}
```
## When to choose which
- Use the manual HStack split when you need full control or a non-standard secondary column.
- Use `NavigationSplitView` when you want a standard system layout with minimal customization.
