fillColor property

WidgetStateProperty<Color?>? fillColor
final

The color used to fill this checkbox.

Resolves in the following states:

This example resolves the fillColor based on the current WidgetState of the CupertinoCheckbox, providing a different Color when it is WidgetState.disabled.
link 
CupertinoCheckbox(
  value: true,
  onChanged: (_){},
  fillColor: WidgetStateProperty.resolveWith<Color>((Set<WidgetState> states) {
    if (states.contains(WidgetState.disabled)) {
      return Colors.orange.withOpacity(.32);
    }
    return Colors.orange;
  })
)

If fillColor resolves to null for the requested state, then the fill color falls back to activeColor if the state includes WidgetState.selected, CupertinoColors.white at 50% opacity if checkbox is disabled, and CupertinoColors.white otherwise.

Implementation

final WidgetStateProperty<Color?>? fillColor;