After I switch to xcode8, and add those files again, those files appear in Compile Sources. Otherwise it will show mach-o linker error.
Xcode9 beta "Add files to" won't add source files to "Compile Sources"?
When you choose "Add FIles to", you get a sheet that allows you to choose the files. Is the Options panel of this sheet displayed? If so, is the target checkbox checked in the target list?
It's the target membership that causes the files to appear in Compile Sources. If you have already added files to the project that aren't in the target, you can display the File tab of the Utilities panel (Command-Option-0), select the files, and check the target membership boxes there.