Undefined symbols for architecture arm64:
"_res_9_ninit", referenced from:
-[UIDevice(HTHelpers) ht_getLocalDNSAddress] in UIDevice+HTHelpers.o
"_res_9_nclose", referenced from:
-[UIDevice(HTHelpers) ht_getLocalDNSAddress] in UIDevice+HTHelpers.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

缺少系统库所致

解决方案：TARGETS->build Phases->Link Binary With Libraries 添加库libresolv.tbd