Xcode 6 Bug: Unknown class in Interface Builder file

I resolved this issue as I was typing the question. I figured I'd answer my question and leave it here for anyone else who may face this issue when using Xcode 6 beta 4.

To resolve this issue, you need to select each of your custom class objects in Storyboard (this includes any custom views, even the custom view controllers themselves).

Then with those objects selected, open the identity inspector and under "Custom Class" you should see the Module option. Finally:

Click inside the Module text box, and press enter.

Or (update 2022), check the "Inherit Module From Target" option.

That's it! The current module for all of my custom objects must have been internally incorrectly set somehow in Xcode 6 beta 4. But there was no visual indication of this in the inspector.

Note that if pressing enter inside the Module text box doesn't work, try selecting the arrow to the right and manually select your current module, then clear the text box and press enter. You can also try pressing enter inside the class text box (although this usually is to resolve a different issue).

https://i.stack.imgur.com/7u8bd.png

Sometimes Xcode missed customModule="AppName" customModuleProvider="target"

To fix it, open storyboard as source code and replace this line:

<viewController storyboardIdentifier="StoryboardId" id="SomeID" customClass="CustomClass"
sceneMemberID="viewController">

to this:

<viewController storyboardIdentifier="StoryboardId" id="SomeID" customClass="CustomClass"
 customModule="AppName" customModuleProvider="target" sceneMemberID="viewController">

I had this problem after renaming a swift class. Solved it by using the @objc directive:

@objc(ForumTopicListViewController) class ForumTopicListViewController

Project with Multiple Targets

In my case I am working on Project with multiple Targets and the issue was "inherit from Target" was unchecked. Selecting "inherit from target" solved my problem

https://i.stack.imgur.com/g6qUI.png

This worked for me..

Check your compiled source, whether that file(e.g; ViewController.m) is added or not, in my case ViewController file was not added so it was giving me the error..

https://i.stack.imgur.com/MqOOq.png

This can happen in any Xcode above 6.0. It happened to me after renaming some ViewController classes in Swift project (but I guess it will happen with Obj-C too). You just have to open the interface builder, go to Identity Inspector of ViewController that had its class renamed, select class and press Enter. That will reassign renamed class to selected ViewController and also reset Module Value which gets lost after renaming the class.

Update for Xcode 8.1 (probably 8.0 too):

Xcode 8.1 just crashes. Simply and annoyingly just crashes and doesn't print anything. I was chasing that phantom crash for an hour just to find out that it was this very same thing - unassigned class in IB. If you're getting some phantom crashes, double check IB for unassigned classes first.

Enabling Inherit Module From Target took the correct target module. That solved the issue.

https://i.stack.imgur.com/bCh1r.png

Sometimes the controller you are providing loses its target membership from the current application. In that case, pressing enter on the "Module" field will do nothing. Go to the controller and make sure that it has target membership set to the current app.

My answer: set custom Module equal to the custom Pod name (in my example - custom class name) like on the screenshot attached

This solution is for a specific case: for custom views classes from Pod (or Carthage) framework.

Infrastructure: XCode8, Swift3

https://i.stack.imgur.com/l4fij.png

Selecting the proper Module for my Custom Class I solved this problem .

Here it is :

https://i.stack.imgur.com/h00Oh.png

I fixed it by doing exactly the opposite of what ChikabuZ suggested (thanks for pointing it out, though). In the storyboard file, find this:

<viewController storyboardIdentifier="StoryboardId" id="SomeID" customClass="CustomClass" customModule="AppName" customModuleProvider="target" sceneMemberID="viewController">

and replace it with this:

<viewController storyboardIdentifier="StoryboardId" id="SomeID" customClass="CustomClass" sceneMemberID="viewController">

I can't believe how many hours I'm losing getting around bugs in the Swift compiler and Xcode 6

I faced this problem in Xcode 8, to resolve it I had to modify storyboard in the text editor.

In general, look up for your control and remove customModule and customModuleProvider from control entity.

Did a trick for me.

I had the same problem.

In my case, Xcode wasn't adding my custom class to: Target > Build Phase > Compile Sources.

So I recommend you to verify if your CustomClass.m is there.

https://i.stack.imgur.com/VorFX.png

I hope this helps you.

You need to check the box "Inherit Module From Target" Checkbox

https://i.stack.imgur.com/ddHdi.png

I faced this issue in Xcode 6.1 when I removed Main.storyboard , the LaunchScreen.xib file and the default ViewController classes from my project.

I fixed it by deleting the Launch Screen File and Main Interface entries from Info.plist

Check if your class has right Target Membership.

I googled everywhere for this. None of the answers work for me until i met 1 dude who asked me to move my project folder to desktop. It just worked automatically. Apparently if you have you project folder to deep in many folders, XCODE actually breaks.

These steps work for me.

1) Clear Derived Data. 2) Remove .h and .m files 3) Create .h and .m files Again

I solved this by opening my storyboard file as source code and using command-F to search for my unknown class and delete the custom class associated with it.

What @gfrs said is correct, you need to set the Module. However I once ran into an issue that my class wasn't listed in the Class dropdown. Eventually I removed the swift file, re-started Xcode and re-created the file. Finally the class was listed and could be used in Storyboard.

Also have a look at this answer, which looks like to solve the 'real' problem I encountered.

I solved this problem by typing in the Module name (unfortunately the drop list will show nothing...) in the Custom Class of the identity inspector for all the View controller and views.

You may also need to indicate the target provider. To achieve this objective you can open the storyboard in sourcecode mode and add the "customModuleProvider" attribute in both ViewController and View angle brackets.

My solution (Xcode 8.1 Swift 3.0):

Unknown class xxx in Interface Builder file.

Open StoryBoard as Source Code and search for xxx. Remove attribute which contains value xxx. Build and Run.

In my case, I added a flag -ObjC to Other Linker Flags in project settings to make it work. Also I tried with -all_load flag and it worked well too.

https://i.stack.imgur.com/dPvya.png

In my case, the class referenced in the Storyboard / xib did not have Target Membership set.

To fix, give that class's .h and .m files the same Target Membership as your other classes.

https://i.stack.imgur.com/NQlvR.png

My solution was to remove @objc from Custom class definition.

I had the same problem with Xcode Version 6.1 (6A1052d). I think the problem appears if you renamed your App / Xcode Project.

My solution was to add the module name in the interface builder manually.

I faced the problem when I ported the storyboard from Swift project to Objective-c project, noticing vvkuznetsov's answer, it turned out the two project using same identifier. I "Product -> Clean" and tap Enter key on the Module and Class text field. the issue went away.

I fixed this along the lines of what Laura suggested but I didn't need to recreate the files.

Using XCode 4, in the Project Navigator, select the .m file that contains the class that it is complaining about

Go to View->Utilities->Show File Inspector (this will show the File Inspector to the right, with that .m-file info)

Open the Target Membership section and make sure that your target is selected for this .m-file

When I added my .m file to my project, it didn't add it to my default target for some reason and that caused me to get the error you mentioned.

My issue was user error. I had a generic UIView in my storyboard and in the Custom Class section of the Identity Inspector I had accidentally changed the name from UIView to gibberish.

All it took to fix was to change it back to UIView.

What only worked for me is actually adding the module name to the xib file...

Sooo, the xib files look like this:

mymodule.MyViewController.xib (Module being the name of the proyect, usually)

HORRIBLE solution in my opinion, but that is supposedly how Apple wants us to do it now.

This question shows 3 possible work arounds back in beta 4 ... apparently Apple has not been very helpful in this situation according to some because they call it "Working as intended."