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iOS
UISegmentedControl
Swift
programming
app development

How do I switch UISegmentedControl programmatically?

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Introduction

To switch a UISegmentedControl segment programmatically in Swift, set its selectedSegmentIndex property. Setting this property changes the visual selection but does not fire the .valueChanged action by default. If you need the value-changed handler to execute, call sendActions(for: .valueChanged) after setting the index. In SwiftUI, bind a @State variable to a Picker with .segmented style and update the variable to switch segments.

UIKit: Setting selectedSegmentIndex

swift
1class ViewController: UIViewController {
2
3    let segmentedControl = UISegmentedControl(items: ["Daily", "Weekly", "Monthly"])
4
5    override func viewDidLoad() {
6        super.viewDidLoad()
7
8        segmentedControl.selectedSegmentIndex = 0 // Default to "Daily"
9        segmentedControl.addTarget(self, action: #selector(segmentChanged(_:)),
10                                   for: .valueChanged)
11        view.addSubview(segmentedControl)
12    }
13
14    @objc func segmentChanged(_ sender: UISegmentedControl) {
15        switch sender.selectedSegmentIndex {
16        case 0: showDailyData()
17        case 1: showWeeklyData()
18        case 2: showMonthlyData()
19        default: break
20        }
21    }
22
23    // Switch programmatically
24    func selectWeekly() {
25        segmentedControl.selectedSegmentIndex = 1
26        // Note: this does NOT trigger segmentChanged automatically
27    }
28}

Triggering the Value Changed Action

Setting selectedSegmentIndex does not fire .valueChanged. To trigger the handler:

swift
1func selectWeeklyAndNotify() {
2    segmentedControl.selectedSegmentIndex = 1
3    segmentedControl.sendActions(for: .valueChanged) // Fires segmentChanged
4}

Or call your handler directly:

swift
1func selectWeeklyAndUpdate() {
2    segmentedControl.selectedSegmentIndex = 1
3    segmentChanged(segmentedControl) // Call handler directly
4}

Deselecting All Segments

Set selectedSegmentIndex to -1 to deselect all segments:

swift
segmentedControl.selectedSegmentIndex = UISegmentedControl.noSegment // -1

This is useful when the segmented control should start with no selection, requiring the user to make an explicit choice.

Setting Up from Storyboard

swift
1class ViewController: UIViewController {
2
3    @IBOutlet weak var filterControl: UISegmentedControl!
4
5    override func viewDidLoad() {
6        super.viewDidLoad()
7        filterControl.selectedSegmentIndex = 0
8    }
9
10    @IBAction func filterChanged(_ sender: UISegmentedControl) {
11        let selectedTitle = sender.titleForSegment(at: sender.selectedSegmentIndex)
12        print("Selected: \(selectedTitle ?? "")")
13
14        // React to selection
15        updateContent(for: sender.selectedSegmentIndex)
16    }
17
18    // Switch programmatically from another action
19    @IBAction func resetTapped(_ sender: UIButton) {
20        filterControl.selectedSegmentIndex = 0
21        filterChanged(filterControl) // Manually trigger update
22    }
23}

Dynamic Segments

Add, remove, and modify segments at runtime:

swift
1let control = UISegmentedControl(items: ["One", "Two"])
2
3// Insert a segment
4control.insertSegment(withTitle: "Three", at: 2, animated: true)
5
6// Insert with an image
7control.insertSegment(with: UIImage(systemName: "star"), at: 0, animated: true)
8
9// Remove a segment
10control.removeSegment(at: 1, animated: true)
11
12// Remove all segments
13control.removeAllSegments()
14
15// Change a segment title
16control.setTitle("Updated", forSegmentAt: 0)
17
18// Enable/disable a specific segment
19control.setEnabled(false, forSegmentAt: 2)

Customizing Appearance

swift
1let control = UISegmentedControl(items: ["Light", "Dark", "Auto"])
2
3// Tint color (iOS 12 and earlier)
4control.tintColor = .systemBlue
5
6// Background and selected colors (iOS 13+)
7control.selectedSegmentTintColor = .systemBlue
8control.backgroundColor = .systemGray6
9
10// Text attributes for normal state
11control.setTitleTextAttributes([
12    .foregroundColor: UIColor.gray,
13    .font: UIFont.systemFont(ofSize: 14)
14], for: .normal)
15
16// Text attributes for selected state
17control.setTitleTextAttributes([
18    .foregroundColor: UIColor.white,
19    .font: UIFont.boldSystemFont(ofSize: 14)
20], for: .selected)

SwiftUI: Picker with Segmented Style

swift
1struct ContentView: View {
2    @State private var selectedFilter = 0
3
4    var body: some View {
5        VStack {
6            Picker("Filter", selection: $selectedFilter) {
7                Text("Daily").tag(0)
8                Text("Weekly").tag(1)
9                Text("Monthly").tag(2)
10            }
11            .pickerStyle(.segmented)
12
13            // Content changes based on selection
14            switch selectedFilter {
15            case 0: DailyView()
16            case 1: WeeklyView()
17            case 2: MonthlyView()
18            default: EmptyView()
19            }
20        }
21    }
22
23    // Switch programmatically
24    func selectMonthly() {
25        selectedFilter = 2 // Automatically updates the Picker
26    }
27}

Using an Enum for Type Safety

swift
1enum TimeFilter: String, CaseIterable {
2    case daily = "Daily"
3    case weekly = "Weekly"
4    case monthly = "Monthly"
5}
6
7struct ContentView: View {
8    @State private var selectedFilter: TimeFilter = .daily
9
10    var body: some View {
11        Picker("Filter", selection: $selectedFilter) {
12            ForEach(TimeFilter.allCases, id: \.self) { filter in
13                Text(filter.rawValue).tag(filter)
14            }
15        }
16        .pickerStyle(.segmented)
17
18        Button("Show Monthly") {
19            selectedFilter = .monthly
20        }
21    }
22}

Common Pitfalls

  • Assuming selectedSegmentIndex triggers .valueChanged: Setting the index programmatically does not fire the action. Call sendActions(for: .valueChanged) or invoke your handler directly if you need the associated logic to run.
  • Using an out-of-range index: Setting selectedSegmentIndex to an index beyond the number of segments crashes with an out-of-bounds exception. Always validate the index: if index < segmentedControl.numberOfSegments.
  • Forgetting UISegmentedControl.noSegment for deselection: Setting the index to an arbitrary negative number may not work on all iOS versions. Use UISegmentedControl.noSegment (which equals -1) for cross-version safety.
  • Not updating content when switching programmatically: When a user taps a segment, .valueChanged fires and your handler runs. When you switch programmatically, you must manually trigger the content update since the handler does not fire automatically.
  • Using wrong Picker style in SwiftUI: Picker defaults to a wheel or menu style. You must explicitly add .pickerStyle(.segmented) to get the segmented control appearance.

Summary

  • Set segmentedControl.selectedSegmentIndex = n to switch segments programmatically in UIKit
  • Call sendActions(for: .valueChanged) after setting the index if you need the action handler to fire
  • Use UISegmentedControl.noSegment (-1) to deselect all segments
  • In SwiftUI, use Picker with .pickerStyle(.segmented) and bind to a @State variable
  • Use an enum with CaseIterable in SwiftUI for type-safe segment values
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