RadioGroup

RadioGroup keeps a small set of radio buttons mutually exclusive: selecting one option clears the previous selection.

It is useful for choices such as billing period, delivery speed, or a small list of modes where exactly one option should be active at a time.

Use it when…

Use RadioGroup when the user needs to choose one item from a short, visible set of alternatives.

For independent on/off choices, use separate checkable controls instead. For a long or dynamic list, a recycled list with explicit selection state is usually a better fit.

How it behaves

Place RadioButton children inside the group and give each button a stable id when application code needs to select or identify it.

check(_:), clearCheck(), and checkedRadioButtonId() are live operations. Call them after the Android view has been realized.

The checked-change listener surface accepts an Android/JNI-compatible listener object. There is no Swift closure convenience for group selection changes in the current API.

Examples

Build a billing-period choice

RadioGroup(id: 2000) {
    RadioButton(id: 2001)
        .text("Monthly")

    RadioButton(id: 2002)
        .text("Annual")

    RadioButton(id: 2003)
        .text("Lifetime")
}
.orientation(.vertical)

The group coordinates the three buttons so only one can remain selected.

Select an option from application state

After the group is on screen, select a button by its id:

func chooseAnnualPlan(_ group: RadioGroup) {
    group.check(2002)
}

The button with id 2002 becomes the selected radio button.

Read or clear the live selection

let selectedID = group.checkedRadioButtonId()

group.clearCheck()

checkedRadioButtonId() returns the current selected button id. clearCheck() removes the group's current selection.

Initializers

Create an empty group, provide its radio buttons directly, or assign an id for later access:

RadioGroup()

RadioGroup {
    RadioButton(id: 2001)
        .text("Standard")
    RadioButton(id: 2002)
        .text("Express")
}

RadioGroup(id: 2000)

Use the inherited LinearLayout configuration when the options should be vertical or horizontal.

Methods

Select a radio button

check(_:) selects the child radio button whose id matches the supplied value.

group.check(2002)

This is a live call, so use it after the native group exists.

Clear the selection

clearCheck() removes the current checked radio button.

group.clearCheck()

Use it when the UI is allowed to return to a no-selection state.

Read the selected id

checkedRadioButtonId() reads the id of the currently checked child from the live group.

let selectedID = group.checkedRadioButtonId()

The Android API uses -1 when no radio button is selected.

Attach Android listener objects

onCheckedChangeListener(_:) configures an Android-compatible RadioGroup.OnCheckedChangeListener object.

group.onCheckedChangeListener(listener)

The listener can be configured before realization, but listener must already be a JNI-compatible listener object; this method does not accept a Swift closure.

onHierarchyChangeListener(_:) follows the same pattern for Android hierarchy-change listener objects.