Palette xib problem in Xcode


I’m developing a plugin using palette in XCode 9.2, Mac OS 10.12.6. (I am a newbie to Objective C.)
By the way, when I create a new project, palette xib has a problem in IBOutlet connection.
It says the File’s Owner has no outlet name for the palette view as below. It is a newly generated project without any changes.

I tried it in XCode 8.3.2 and it has the similar problems and upgrades XCode to 9.2.
Please let me know what is the problem and how I can solve it?

Thanks in advance.

Did you set the class of “File Owner” to ERR (That is not a good class name. Use something longer with a private suffix, like your initials).

how about this, “CollectHangul”. It also has the same problem. All the IBOutlets are not connected :frowning:

OMG, It works! I did put a wrong class name.

Thanks a lot!