xcode中找不到 XXX.dylib 了，比如libz.tbd 如果要用到 libz.dylib，可以用下面的办法，来自 Stack Overflow。

1. Go to Build Phases >Link Binary with Librairies > + > Add other
2. Once in the file selection window do “CMD”+Shift+G (Go to folder) and type /usr/lib/
3. From /usr/lib you can add : libz.dylib and more…
4. Compile and have fun