The method 'withValues' isn't defined for the type 'Color'

i have error with withValues my flutter version is 3.24.5 my code:

import 'package:eClassify/ui/theme/theme.dart';
import 'package:flutter/material.dart';

enum AppTheme { dark, light }

final appThemeData = {
  AppTheme.light: ThemeData(
    // scaffoldBackgroundColor: pageBackgroundColor,
    brightness: Brightness.light,
    //textTheme
    useMaterial3: false,
    fontFamily: "Manrope",
    textSelectionTheme: const TextSelectionThemeData(
      selectionColor: territoryColor_,
      cursorColor: territoryColor_,
      selectionHandleColor: territoryColor_,
    ),
    switchTheme: SwitchThemeData(
      thumbColor: const MaterialStatePropertyAll(territoryColor_),
      trackColor: MaterialStateProperty.resolveWith((states) {
        if (states.contains(MaterialState.selected)) {
          return territoryColor_.withValues(alpha: 0.3);
        }
        return primaryColorDark;
      }),
    ),
    colorScheme: ColorScheme.fromSeed(
        error: errorMessageColor,
        seedColor: territoryColor_,
        brightness: Brightness.light),
  ),
  AppTheme.dark: ThemeData(
    brightness: Brightness.dark,
    useMaterial3: false,
    fontFamily: "Manrope",
    textSelectionTheme: const TextSelectionThemeData(
      selectionHandleColor: territoryColorDark,
      selectionColor: territoryColorDark,
      cursorColor: territoryColorDark,
    ),
    colorScheme: ColorScheme.fromSeed(
        error: errorMessageColor.withValues(alpha: 0.7),
        seedColor: territoryColorDark,
        brightness: Brightness.dark),
    switchTheme: SwitchThemeData(
        thumbColor: const MaterialStatePropertyAll(territoryColor_),
        trackColor: MaterialStateProperty.resolveWith((states) {
          if (states.contains(MaterialState.selected)) {
            return territoryColor_.withValues(alpha: 0.3);
          }
          return primaryColor_.withValues(alpha: 0.2);
        })),
  )
};

i have try to create extension method but still didn't work. ...........................................................................................................................................................................................................................................

This is because of a change introduced in Flutter version 3.27, see here, and you are using an earlier version in which withValues does not exist.

Either upgrade to the latest Flutter, or if you want to use your current version, instead of:

territoryColor_.withValues(alpha: 0.3)

use this:

territoryColor_.withOpacity(0.3)