ndefined symbols for architecture x86_64:

問題 ：文件刪掉，重新導入，報“ndefined symbols for architecture x86_64:

"OBJC_CLASSKaTeX parse error: Expected group after '_' at position 103: …nt: _OBJC_CLASS_̲_goodListForExpandViewModel)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
”

原因：編譯連接斷開；

解決辦法：Build Phases -Compile Sources -+進來