IB Designables gives strange warning when using a custom class

This question seems to be getting some attention again so I'll give an update.

This issue existed in a Obj-C and Swift mixed project. So the Class in question was a Swift Class.

When making Swift classes available in Obj-C, you can use the following syntax

@objc(NTHamburgerButton) public class NTHamburgerButton : UIButton {}

Otherwise in your {Project-Name}-Swift.h file that Xcode Creates you will see that it generates these unique class names like that from the question.

The only real issue here was that the NTHamburgerButton.swift file was not being included in the Product I was looking at the at time, but if I switched targets, it worked fine. Thus the intermittent issue.

For me both solutions of Codermonk and specialvict was necessary, but not enough.

I also had to turn on Inherit From Target in Interface Builder:

This did the trick for me.

I've encounter the same problem, and I found an answer from other question: enter link description here

I just Refresh All Views

It works to me. Hope it helps you too.