How can I set the default state of a UISegmentedCo

Question

Is there a way to set the starting selected segment in a UISegmentedControl in Interface Builder, or do I have to do it in the code? If it's in the code, is viewDidLoad the best place to set it?

Answer 1

In Interface Builder when you select UISegmentedControl object on your UI, then in attributes pane, in segment control there's segment drop down menu, select segment that you want selected (0,1 and so on) and tick the 'selected' option below it.

Answer 2

From code, you can just do self.segmentedControl.selectedSegmentIndex = someDefaultIndex.

Whether you should set it in viewDidLoad: or not depends entirely on the structure of your application. For example, if your app is starting up and loading the view for the first time and needs to set the control to whatever value it had during the previous run of the app, then it definitely makes sense to do it there.

Answer 3

If you don't use storyboards and want to set a default index after some setup/networking like me, this little snippet will select something if the user hasn't. I placed this in my subclass of UISegmentedControl, but you could place this anywhere. (Swift 3)

Decl: var UISegmentedControlNoSegment: Int { get }
Desc: A segment index value indicating that there is no selected segment. See selectedSegmentIndex for further information.

---

Short version:

if selectedSegmentIndex == UISegmentedControlNoSegment {
    selectedSegmentIndex = initialIndex
}

---

Longer version

func reloadData() {
    guard let numberOfItems = dataSource?.numberOfItems() else {
        return
    }

    removeAllSegments()

    for index in 0...numberOfItems {
        insertSegment(with: $image, at: index, animated: false)
    }

    if selectedSegmentIndex == UISegmentedControlNoSegment {
        selectedSegmentIndex = initialIndex
    }
}

Answer 4

After clicking the Segmented Control go to where you created the segments and choose the one you want be default. Then below that there will be a Box with "Selected" by it. Select that and it will be default.