toggleCategory method
Implementation
void toggleCategory(UCategoryResponse cat, bool on) => on ? selectedCategories.add(cat) : selectedCategories.removeWhere((UCategoryResponse x) => x.id == cat.id);
void toggleCategory(UCategoryResponse cat, bool on) => on ? selectedCategories.add(cat) : selectedCategories.removeWhere((UCategoryResponse x) => x.id == cat.id);