Flutter ThemeData初始化报错：'colorSchemeSeed == null || primaryColor == null'不成立

错误原因 #

你同时给ThemeData设置了colorSchemeSeed和primaryColor，这两个参数是互斥的。colorSchemeSeed的作用是自动生成一套完整的ColorScheme（包含primaryColor在内的所有主题色），手动设置primaryColor会和自动生成的颜色冲突，所以Flutter用断言阻止这种矛盾配置。

解决方案 #

二选一即可：

方案1：保留colorSchemeSeed，移除primaryColor

如果需要自定义primaryColor，直接在colorScheme里指定，覆盖自动生成的值：

// Our light/Primary Theme
ThemeData themeData(BuildContext context) {
  return ThemeData(
    appBarTheme: appBarTheme,
    colorSchemeSeed: kAccentLightColor,
    scaffoldBackgroundColor: Colors.white,
    colorScheme: ColorScheme.light(
      primary: kPrimaryColor, // 在这里设置自定义primaryColor
      secondary: kSecondaryLightColor,
      // on light theme surface = Colors.white by default
    ),
    iconTheme: const IconThemeData(color: kBodyTextColorLight),
    floatingActionButtonTheme:
        const FloatingActionButtonThemeData(foregroundColor: kAccentIconLightColor),
    primaryIconTheme: const IconThemeData(color: kPrimaryIconLightColor),
    textTheme: GoogleFonts.latoTextTheme().copyWith(
      bodySmall: const TextStyle(color: kBodyTextColorDark),
      bodyMedium: const TextStyle(color: kBodyTextColorDark),
      bodyLarge: const TextStyle(color: kBodyTextColorDark),
      headlineMedium: const TextStyle(color: kTitleTextDarkColor, fontSize: 32),
      headlineLarge: const TextStyle(color: kTitleTextDarkColor, fontSize: 80),
    ),
  );
}

方案2：保留primaryColor，移除colorSchemeSeed

如果不需要用colorSchemeSeed自动生成颜色，直接删掉这个参数：

// Our light/Primary Theme
ThemeData themeData(BuildContext context) {
  return ThemeData(
    appBarTheme: appBarTheme,
    primaryColor: kPrimaryColor,
    scaffoldBackgroundColor: Colors.white,
    colorScheme: ColorScheme.light(
      secondary: kSecondaryLightColor,
      // on light theme surface = Colors.white by default
    ),
    iconTheme: const IconThemeData(color: kBodyTextColorLight),
    floatingActionButtonTheme:
        const FloatingActionButtonThemeData(foregroundColor: kAccentIconLightColor),
    primaryIconTheme: const IconThemeData(color: kPrimaryIconLightColor),
    textTheme: GoogleFonts.latoTextTheme().copyWith(
      bodySmall: const TextStyle(color: kBodyTextColorDark),
      bodyMedium: const TextStyle(color: kBodyTextColorDark),
      bodyLarge: const TextStyle(color: kBodyTextColorDark),
      headlineMedium: const TextStyle(color: kTitleTextDarkColor, fontSize: 32),
      headlineLarge: const TextStyle(color: kTitleTextDarkColor, fontSize: 80),
    ),
  );
}

内容的提问来源于stack exchange，提问作者Atik19