NSClassFromString返回nil？

NSString *classString = [string stringByAppendingString:languageIdentifier];
Class languageClass = NSClassFromString(classString);

一直是nil很奇怪

最后终于知道了怎么解决
“Other Linker Flags” -ObjC

记录一下
参考链接https://cloud.tencent.com/developer/ask/46180