trackOutlineColor property

This example resolves the trackOutlineColor based on the current WidgetState of the Switch, providing a different Color when it is WidgetState.disabled.

Switch(
  value: _value,
  // If `onChanged` is null, this switch is disabled.
  // If `onChanged` is not null, this switch is enabled.
  onChanged: _nullableOnChanged,
  trackOutlineColor: WidgetStateProperty.resolveWith<Color?>((
    Set<WidgetState> states,
  ) {
    if (states.contains(WidgetState.disabled)) {
      return Colors.orange.withValues(alpha: .48);
    }
    return null; // Use the default color.
  }),
)