Undefined symbols for architecture x86_64:
"_OBJC_CLASS_$_UserDetailInfoView", referenced from:
objc-class-ref in ViewController.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
出现这种错误，打开UserDetailInfoView.m文件，点击右边的Target Membership 勾选上Test就行了