Ответ 1
Вы могли бы сделать
if ([TheWantedClass class]) {
// The class exists so run code
} else {
// The class doesn't exist so use an alternate approach
}
или
if (NSClassFromString(@"TheWantedClass") != nil) {
// The class exists
} else {
// The class doesn't exist
}
https://developer.apple.com/documentation/foundation/1395135-nsclassfromstring