I'm trying to put a colour behind my IconButtons, using the technique suggested in https://github.com/flutter/flutter/issues/18220

I'm having a problem trying to use it for the back button. My code is complaining

This expression has a type of 'void' so its value can't be used.

And yet I have it typed to VoidCallback. Thoughts?

Thanks.

SliverAppBar(
  ...
  leading: InkyIconButton(
    icon: Icons.arrow_back_ios,
    pressFunction: Navigator.of(context).pop(),
  )
)

class InkyIconButton extends StatelessWidget {
  const InkyIconButton({
    Key? key,
    required this.icon,
    required this.pressFunction,
  }) : super(key: key);
  final IconData icon;
  final VoidCallback pressFunction;

  @override
  Widget build(BuildContext context) {
    return Ink(
      padding: const EdgeInsets.fromLTRB(8.0, 0, 0, 0),
      decoration: const ShapeDecoration(
        color: Colors.black,
        shape: CircleBorder(),
      ),
      child: IconButton(
          padding: EdgeInsets.zero,
          onPressed: () => pressFunction,
          icon: Icon(icon)),
    );
  }
}

CodePudding user response：

Try pressFunction(). The parenthesis actually make the function get called.