Unknown class MyClass in Interface Builder file error at runtime

Question

Even though Interface Builder is aware of a MyClass  I get an error when starting the application   This happens when MyClass is part of a library  and does not happen if I compile the class directly in the application target

User · Answer

I FINALLY fixed this  I had forgotten to add the following code to my  m file    implementation MyTableViewCell   end   So it was being caused because I had made a placeholder  interface for my table cell  that had a connection to an element in the  xib file  but there is a bug in Interface Builder where if no  implementation is specified for a class  it can t find it   I had gone through all of the steps from other forums of viewing the  xib as source and seeing MyTableViewCell even though I had commented it out of my code   I had tried resetting the simulator   I even tried breaking all of my classes up into separate files named the same as the interfaces  but nothing worked until this   P S  in my experience  it doesn t matter if the names of the  h  m files are different from the names of the  interface   I have several files containing more than one  interface and they work fine   P P S  I have a more detailed explanation of why UITableViewCell and UICollectionViewCell cause this error at https   stackoverflow com a 22797318 539149 along with how to reveal it at compile-time using registerClass  forCellWithReuseIdentifier

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I fixed this by copying the text from my class h and  m  deleting those class files from the project  and creating new class h and  m files with the same name using  Add File   Then I pasted the code back into the new files  and everything worked great  Somehow the files weren t linked correctly when they were created  I didn t need to use any linker flags after that

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I had   Unknown class favouritesButton in Interface Builder file   and tracked it down to a storybook scene where the button in question had a bogus custom class of  favouritesButton  in the Class field at the top of the Identity Inspector  I meant to put that value in the next field  Identity Label     Changing this to  UIButton  solved the problem

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I just want to add this answer since most if not all the answers here assume that the class actually exists   it s just that the linker compiler is too dumb to see it   thus the answers revolve around either alerting the linker to the existence of the class or creating a hack to  force  exist it     my problem happens when this message is actually talking about a non-existent class   so an example would be me reverting back to an old git revision that has no knowledge of a certain class   yet the compiler complains that the said class doesn t exist     solution    Nuke the whole thing  first delete all the build files etc by deleting all the contents in this directory    Library Developer Xcode DerivedData delete the app from the phone itself  and clear the simulator contents if you are using a simulator    you should be good to go after that

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My case - Trying to use a Class from a swift framework in my objective c project  I got this error  Solution was to add Module  swift framework  of the class in Interface builder  Storyboard as shown below  Nothing else

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Despite the  Unknown class MyClass in Interface Builder file   error printed at runtime  this issue has nothing to do with Interface Builder  but rather with the linker  which is not linking a class because no code uses it directly   When the  nib data  compiled from the  xib  is loaded at runtime  MyClass is referenced using a string  but the linker doesn t analyze code functionality  just code existence  so it doesn t know that   Since no other source files references that class  the linker optimizes it out of existence when making the executable   So when Apple s code tries to load such a class  it can t find the code associated with it  and prints the warning   By default  Objective-C targets will have -all load -ObjC flags set by default  which will keep all of the symbols   But I had started with a C   target  and didn t have that   Nevertheless  I found a way around this  which keeps the linker aggressive   The hack I was originally using was to add an empty static routine like     void  keepAtLinkTime    which does nothing  but that I would call once  such as   int main  int argc  char   argv         MyClass  keepAtLinkTime         Your code      This would force the linker to keep the whole class  and the error disappears   As jlstrecker pointed out in the comments  we do not really need to add a  keepAtLinkTime method   Simply calling an existing one  such as       MyClass class     does the trick  as long as you derive from an NSObject    Of course  you can call this in any location of your code   I guess it could even be in unreachable code   The idea is to fool the linker into thinking that MyClass is used somewhere so that it isn t so aggressive in optimizing it out   Xcode 6 3 2  amp  Swift 1 2  Swift definition of view  Be sure to override init coder aDecoder  NSCoder   Objective-C definition of view controller  And  a nib in a pear tree   Add Module Name to Nib details inspector where you pick your class

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I saw this error when I changed a class name  despite updating all relevant  h and  m  Turned out  I had missed updating  customClass  value in the  storyboard files  That resolved the problem

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I had this issue when I had made a new project with the same name and had run them both in the simulator  I renamed one of the projects  deleted the app in the simulator  then ran a clean and re-build

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The best way to remove the error is  1  Select the Class File   m  2  Under  Target Membership    check  the Project name entry

User · Answer

I tried most of the solutions you guys suggested above but to no avail   After reading the solution from user776904 s I suspected I was having the same issue as I had rebuilt my app from the ground up but copied the xib files from the previous project   I suspected the xib file had a reference to the old project that was causing my error so I simply deleted my mainwindow ipad xib file and copied in a new one from a clean new project   This solved it  And I was not game enough to  start changing bits of the xib file in its source code

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In my case problem was a dead IBOutlet link  Once this was fixed everything was good again

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After trying most of the suggestions here wihtout success  I just renamed my class and then renamed it manually in the xib file  with open as source code   Problem then went away

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I had  Unknown class RateView in Interface Builder  where RateView was a subclass of UIView  I had dropped a UIView onto my Storyboard scene and changed the Custom class field to RateView  Still  this error appeared   To debug  I changed the name of my class to RateView2 and changed all references to match except the Custom class field of the UIView  The error message still appeared as before with RateView as the missing class  This confirmed that the error message was related to the value of the Custom class field  I changed this value to RateView2 and the error message changed to  Unknown class RateView2 in Interface Builder   Progress of sorts   Finally  I inspected the source code files themselves in the File Inspector  There I discovered that the source code file  which I had copied from a tutorial  was not associated with my Target  In other words  it had no Target Membership  I checked the box that made the class s source code file a member of the target app and the error message went away

User · Answer

Go to Build Phases-  Compile Sources and add your new  m files

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In my case I had used a storyboard from another project  After looking at the storyboard file xml  e g  in TextWrangler  I noticed that one of the  customModule  xml attribute values for a controller was wrong  it was still referencing the old project   Manually changing this fixed the problem

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I ran into this in Swift   Moving the  xib file into the project s Base lproj folder got rid of this error

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This    Unknown class  in Interface Builder file    error at runtime come if you have more then one StoryBoard and one of the StoryBoard using the  which is not really exists

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Per Apple Documentation     For 64-bit and iPhone OS applications  there is a linker bug that   prevents -ObjC from loading objects files from static libraries that   contain only categories and no classes  The workaround is to use the   -all load or -force load flags    In short add -all load to  other linker  flags in your  Build Settings  and you should be good   http   developer apple com library mac qa qa1490  index html

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This drove me nuts for a bit and none of the suggestions above helped me get rid of the error    Luckily I only had one IB object using the class so I just deleted it and added it back with the same class specified    Error went away

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just add below code at the starting of appdelegate applicatoindidfinishlanching method then it will works fine      myclass class

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I did run into this problem today using Swift   I changed a class Model h   Model m to a Model swift   This object was used in Interface Builder with the class   Model    As soon as I replaced the object the class could no longer be loaded   What I had to do was to change the class reference in IB from   Class   Model Module      to   Class   Model Module    lt TARGETNAME gt    You ll find the  lt TARGETNAME gt  in the build settings  It is also the name that shows up in your generated Swift-Header   import  TARGETNAME-Swift h

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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

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In my case I got this error because I d tried to save some work by creating a new project and then deleting several of the source files and copying over the source files of the same name from the working project  I also copied my MainStoryBoard file which was looking for my RootViewController  However  when I had deleted the original RootViewController and then added in the RootViewController from the previous product  evidently the Add Files operation failed to  check  the target box as suggested above  By merely visting all of the newley imported   m  files and making sure that the target membership box was checked  all was well  I think what was happening was that the storyboard file was looking for a class that had been  excluded  from the link because the target membership was unchecked  Making sure the required files for the target are so designated in the target membership in the file inspector did the trick  Thanks Pat   see above

User · Answer

Go to the  ProjectName    click on it   and then go the  Build phases  tab   and then click on the   compile sources    and then click on     button   a window will appear   the choose  MyClass m  file and then click  add     Build the Project and Run it   the problem will surely get solved out

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In my case I get this error message by a very stupid mistake by me  on interface builder I wanted to set the identifier of a UITableViewCell  but I typed the identifier accidentally to the  Custom class  entry in interface builder    I made cells 1000 times before

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It s a Xcode4 cache problem  just delete all folders under  Users your user Library Application Support iPhone Simulator 4 3 Applications   Also if you have the same issue testing on your iPhone  delete the old app before running it     Good luck  Pascual

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This problem happened to me when I added a picker view and then removed it  In case it will help someone  here s how I solved it finally    Open Document Outline at XCODE  don t know what is Document Outline  I didn t also - google it         Find the Scene that makes the warning message appear  in the document outline window  On the problematic scene  stand  click  on View  and then in the Utility  google it  window select the Identity inspector tab and change back the custom class name to default UIView    That t it

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A lot of answers here but none was the solution   I tracked it down to the storyBoard where the controller had an Invalid custom class  class does not exist after I renamed it

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In my case  the custom UIView class is in an embedded framework  I changed the custom UIView header file to  project  to  public  and include it in the master header file

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From interface builder storyboard is referred to a class that is not available   If the  is a known class it is not linked   If the  is not a class or just some characters it is probably a typo  In that case check all the fields in the view controller for this  unknown class    In the  Identity Inspector   3rd from left in the block  Custom Class  is one field  Class  which probably contains the wrong value  Normally it lists the field type  UIView   UILabel etc

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Not only in project settings  but in Target setting also u have to add  -all load -ObjC flags    Core-Plot  Unknown class CPLayerHostingView in Interface Builder file

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In my case it was because I declared a subclass of a subclass of a UITableView cell in the  h file  the declaration of both subclasses were in the same  h file   but forgot to make an empty implementation of that second subclass in the  m file   don t forget to implement any subclass of a subclass you declare in the  h file   sounds simple  but easy to forget because Xcode will do this for you if you are working with one class per  h  m file

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In my case it was showing an error for a class that didn t even exist  I suspected it was something that got borked in the storyboard file  If you don t recognize the class file in the error try this   1  open your project in sublime or another good editor  Search for the class being referred to  2  remove the whole bit that says  customClass  UnrecognizedClassName    3  save it   4  return to xcode and clean the project  and try running it now    worked for me

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In my case  I have XCode6  the specified class  m file end up in the wrong place in build phase - It should have been under Compile Sources  but end up in the

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This happens because the  xib has got a stale link to the old App Delegate which does not exist anymore  I fixed it like thus    Right click on the  xib and select Open as   Source code In this file  search the old App delegate and replace it with the new one

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I tried this  and other  answers listed on this site  none of which sorted it for me  This comments  from http   www iphonedevsdk com forum iphone-sdk-development 43330-unknown-class-interface-builder-file html   helped      After searching and searching and searching  I finally discovered the name of this deleted class hidden in a file  I had to open the interface builder files in X-code  by right clicking on them and choosing  view as source code   Then searching for it came up with   lt object class  NSMutableArray  key  dict values  gt   lt bool key  EncodedWithXMLCoder  gt YES lt  bool gt   lt string gt com apple InterfaceBuilder IBCocoaTouchP lu gin lt  string gt   lt string gt  this was the class name  lt  string gt     Simply removing that last line doesn t fix it unfortunately  complaining that there are the wrong number of items in the file  You need to remove the corresponding line in the section of lines above it  which refers to CustomClass

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I keep having this error with WatchKit over and over again and it seems to be when there is a user interface element that isn t tied to an outlet in code  I guess this is required in WatchKit   class InterfaceController  WKInterfaceController        IBOutlet weak var table  WKInterfaceTable      Important note  just connect the outermost element  For instance if you try to also give a connection for something within the table like a label inside a row you will get a compiler error saying the outlet is invalid and cannot be connected to repeating content

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I had this error crop up today when converting my aaLuminate app to Universal under Xcode 4   This app is based on the utility template and was originally built under Xcode 3    To save time I copied the iPhone Main and Flipside Views across to appropriate names on the Universal app  I experienced the  Unknown class x in Interface Builder file  error  In my case it was nothing in the XIB files or targets   I had also copied the aaLuminate-Info plist file across for other reasons - this had an old key  Main nib file base name  set to MainWindow   As soon as I deleted this key it fixed the problem

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I added the file Under Build Phase in Targets and the issue got resolved  For the steps to add the file  see my answer at   Apple Mach-O Linker error  APActivityIcon

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In my case I had deleted a class called  viewController  not realising it was selected with the storyboard s identity inspector  under  Custom Class  up the top    You just have to simply select the correct class for the view controller in your identity inspector s Custom Class field or add a new class to your project and select that one as your Custom Class   Worked for me

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In my case  the class couldn t be found because it was a classed defined in an extension inside the framework like so   extension Buttons       public class MyButton  UIButton                            When I extracted the class from the extension  the Storyboard could finally find the class  MyFrameworkButton     extension Buttons       public typealias MyButton   MyFrameworkButton    public class MyFrameworkButton  UIButton

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This problem does not seem to get outdated   I had the same issue with Xcode 8 and solved it similiar like smilebot    Open your storyboard file as  Source code  within Xcode    Search for the class being referred to  amp  remove the whole bit that says   customClass  UnrecognizedClassName    Open your storyboard file as  interfacebuilder - storyboard  again and rebuild your app

User · Answer

Just remove the MyClass m and  h and add them to project again is work for me

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Sometimes IBuilder missed customModule  AppName  customModuleProvider  target    To fix it  open storyboard as source code and replace this line    lt viewController storyboardIdentifier  StoryboardId  id  SomeID  customClass  CustomClass  sceneMemberID  viewController  gt    to this    lt viewController storyboardIdentifier  StoryboardId  id  SomeID  customClass  CustomClass   customModule  AppName  customModuleProvider  target  sceneMemberID  viewController  gt

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In my case was a misspelling  Custom Class   name  Make sure that you check your storyboard for the custom classes that you defined

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This doesn t really have anything to do with Interface Builder  what s happening here is the symbols aren t being loaded from your static library by Xcode  To resolve this problem you need to add the -all load -ObjC flags to the Other Linker Flags key the Project  and possibly the Target  Build Settings    Since Objective-C only generates one symbol per class we must force the linker to load the members of the class too by using the -ObjC flag  and we must also force inclusion of all our objects from our static library by adding the -all load linker flag  If you skip these flags sooner or later you will run into the error of unrecognized selector or get other exceptions such as the one you ve observed here

[cocoa] "Unknown class <MyClass> in Interface Builder file" error at runtime

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