ScrollableTabBar

ScrollableTabBar is an iOS UIKit control for presenting an ordered selection whose overflow items remain horizontally reachable.

Warning

The preferred floating presentation relies on undocumented UIKit APIs and runtime behavior. Its availability, exact Liquid Glass appearance, and App Store acceptance are not guaranteed.

Requirements

• iOS 18.0+
• Swift 6.3+

State Ownership

The app remains the source of truth for each item's domain identity, membership and order, selected value, and corresponding content. ScrollableTabBar projects that selection into UIKit. Create a new control when membership or order changes.

See Selection Ownership for programmatic and user-driven selection behavior.

Quick Start

import ScrollableTabBar
import UIKit

@MainActor
final class DashboardViewController: UIViewController, ScrollableTabBarDelegate {
    enum Section: Hashable {
        case summary
        case activity
        case settings
    }

    private var selectedSection: Section = .summary

    private lazy var sectionControl: ScrollableTabBar<Section> = {
        let control = ScrollableTabBar(
            items: [
                .init(id: .summary, title: "Summary"),
                .init(id: .activity, title: "Activity"),
                .init(
                    id: .settings,
                    title: "Settings",
                    image: UIImage(systemName: "gear")
                ),
            ],
            selectedID: selectedSection
        )
        control.accessibilityLabel = "Dashboard Section"
        control.delegate = self
        return control
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        navigationItem.titleView = sectionControl
        showSection(selectedSection)
    }

    func scrollableTabBar(
        _ tabBar: ScrollableTabBar<Section>,
        didSelect selectedID: Section
    ) {
        selectedSection = selectedID
        showSection(selectedID)
    }

    private func showSection(_ section: Section) {
        // Render application content for `section`.
    }
}

Presentation

When its expected UIKit runtime contract is available, the control uses the system floating-tab presentation. Otherwise, a public UIKit fallback preserves selection, ordering, enablement, and event semantics. Exact layout and appearance are not API guarantees.

Testing

Run package tests on an iOS Simulator:

xcodebuild test \
  -workspace ScrollableTabBar.xcworkspace \
  -scheme ScrollableTabBarTests \
  -destination 'platform=iOS Simulator,name=iPhone 17,OS=latest'

Run the external public-product contract from its separate package:

cd ContractTests
xcodebuild test \
  -scheme ScrollableTabBarProductContract-Package \
  -destination 'platform=iOS Simulator,name=iPhone 17,OS=latest'

Documentation

• ScrollableTabBar Documentation

License

ScrollableTabBar is available under the MIT License. See LICENSE.