generateCupertinoTheme method

void generateCupertinoTheme(
  1. CupertinoThemeManagerData themeData
)

Make sure ThemesManager exist in the widget tree, above of the widget where you are trying to add new themes.

builder: (context, child) {
  ...
  ThemeManager.of(context).generateTheme(
    CupertinoThemeManagerData(
        key: <themeKey>,
        data: <ThemeData>,
    )
  );
  return child;
},

Implementation

void generateCupertinoTheme(
  CupertinoThemeManagerData themeData,
) {
  _cupertinoThemes[themeData.key] = themeData;
}