Missing from the target
It's not unusal to see the following error when attempting to use a new framework or class:
_OBJC_CLASS_$_'XYZ'
There are mainly two reasons why this error occurs.
- Forgotten to include a framework that you are attempting to use.
- A class's
.m
file isn't included in the Target.
See below for more information on both these possible causes.
Missing framework
Lets use the example error of _OBJC_CLASS_$_CoreData
. If when adding Core Data to your project manually, you receive a similar set of errors as below it is because you have forgotten to include the Core Data framework.
"_OBJC_CLASS_$_NSManagedObjectModel", referenced from:
objc-class-ref-to-NSManagedObjectModel in AuditorAppDelegate.o
"_OBJC_CLASS_$_NSEntityDescription", referenced from:
objc-class-ref-to-NSEntityDescription in CoreDataAccess.o
"_OBJC_CLASS_$_NSFetchRequest", referenced from:
objc-class-ref-to-NSFetchRequest in CoreDataAccess.o
"_OBJC_CLASS_$_NSManagedObjectContext", referenced from:
objc-class-ref-to-NSManagedObjectContext in AuditorAppDelegate.o
"_OBJC_CLASS_$_NSPersistentStoreCoordinator", referenced from:
objc-class-ref-to-NSPersistentStoreCoordinator in AuditorAppDelegate.o
"_NSSQLiteStoreType", referenced from:
_NSSQLiteStoreType$non_lazy_ptr in AuditorAppDelegate.o
(maybe you meant: _NSSQLiteStoreType$non_lazy_ptr)
ld: symbol(s) not found
collect2: ld returned 1 exit status
To solve this you just need to added the missing framework.
Missing class
If you get a _OBJC_CLASS_$_'XYZ'
error it is most likely because .m
file is not being included as part of your target.
To add it to a target in Xcode 3:
- Open
.m
file - If top section is closed open it - this section should contain "yourclassname".m (click on image below)
- Tick the checkbox at end of this row
- Rebuild your project and enjoy
To reinstate it as a target in Xcode 4:
- Select project in "Project navigation" side menu
- Select interested Target
- Select "Build Phases" tab
- Expand "Compile Sources
- Scroll down to the bottom of the expanded view and click on the "+" button
- In the pop up window that appears navigate to interested file and double click (or highlight and press add button)
- Rebuild your project and enjoy
What do you think? Let me know by getting in touch on Twitter - @wibosco