I got this error when I press build+debug:
ld: duplicate symbol .objc_class_name_BlogTableItemCell in /Users/fabian/Development/Workspaces/iphone_experiments/xcode_build_output/MausLog.build/Debug-iphonesimulator/MausLog.build/Objects-normal/i386/BlogTableItemCell-3733583914888A7B.o and /Users/fabian/Development/Workspaces/iphone_experiments/xcode_build_output/MausLog.build/Debug-iphonesimulator/MausLog.build/Objects-normal/i386/BlogTableItemCell-3733583914888A7B.o
collect2: ld returned 1 exit status
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 failed with exit code 1
You could also get this error if you mistakenly let Xcode's auto-complete for #import statements specify the '.m" file for the 'duplicate' class instead of the '.h'.
It seems that you are compiling the same BlogTableItemCell class two times in different places of your code. This may happen in the following cases.
You have put the same class
implementation into two different
files;
You actually have just one
implementation of this class, however
you are also linking in your project a framework
or library containing a class whose
name is exactly the same of yours.
Try finding in the whole project your class and make sure only one copy is available within your project.
For me, changing 'No Common Blocks' from Yes to No ( under Targets->Build Settings->Apple LLVM - Code Generation )
I had a similar problem due to poor defining of consts.
I had defined a const in my header:
int const kCropLocationTop = 1;
This was presumably imported multiple times. To fix i changed the header def as follows:
extern int const kCropLocationTop;
and moved the assigning of the const to the .m file:
int const kCropLocationTop = 1;
Hope that helps anyone who's as ignorant of simple objective c concepts as I am!
iPhone: Duplicate Symbol Error? by user576924
answered it correctly for me. However to find the offending gremlin this ZSH snippet.
grep "import.*\.m" **/*.[hm]
Will immediately tell you where your error is.
By mistake the source file was included twice in the Project -> Build Phase -> Compile Sources. Removing one of them solved the problem.
The most common reason for this error is importing an xyz.m file instead of the xyz.h file.
Check if your imports contain something like
#import "----.m"
Just to add; Using Xcode to generate subclassed managed objects (Core Data) can sometimes duplicate the generated files. For me the fix was to delete the generated files and re-generate them.
I just ran into this problem myself. For the list, here's another possibility:
Duplicated linking line in the project file.
I caused this merging conflicts on a SVN update, when I accidentally duplicated a line.
It happened to me, too. In my case, one (just one) of my core data automatically generated classes was inserted twice. I spotted the duplication by looking at Build Phases...Compile Sources. Simply deleting one of the occurrences solved the problem.
Adding another possible cause to the list... you may have mistakingly created multiple constants in the implementation file, but outside of the implementation, with the same name.
In HeaderFileOne.m
NSString * const kCoolConstant = #"cool";
In HeaderFileTwo.m
NSString * const kCoolConstant = #"cool";
So changing one of those constant names would fix the compile error.
This may help someone
I got this error because I duplicate a ViewController and then renamed it. So when I compile I got this error. The reason was in both of the view controllers there was a "float" variable with same name i.e "float padding=10.0" which I had defined on class level.
Renaming the name of the above mentioned variable in One of the view controllers solved my problem.
I also faced to this problem. My solution was rename one of global variable, which has the same name as one in other class. Hope this helps
The same thing happened to me while I was playing with localizable xib files, accidentally I have created two implementation files and appereantly that caused the problem in my case. After deleting / recreating the implementation file without doing the same mistake, the error was fixed.
One of our developers left the "libSoomla*" project files in there twice. I removed the duplicate soomla files, re-built, and that fixed it!
Hope it helps.
In may case, I followed some instructions to build a newer version of Subversion which directed me to create this symbolic link:
ln -s /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/ /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.10.xctoolchain
Now I'm really a Windows guy so it wasn't immediately obvious to me - but removing the link fixed it for me (after restarting XCode):
rm /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.10.xctoolchain
Phew.
(The actual error I got was the one described here:
build error duplicate symbols arclite.o)
Make sure that you didn't import .m File . For me this happen I added #import "SchoolCommuterHome.m" instead of #import "SchoolCommuterHome.h"
Related
I was trying to create NSManagedObject subclasses (2 related entities) automatically in Xcode. They are generated like this:
However, before I do anything further, when I tried to build and run it, a link error occur, as shown:
duplicate symbol _OBJC_CLASS_$_Photo in:
/Users/Kefeng/Library/Developer/Xcode/DerivedData/Photomania-aellrakjngugnzcgrleiytvrfvyt/Build/Intermediates/Photomania.build/Debug-iphonesimulator/Photomania.build/Objects-normal/x86_64/Photo+CoreDataClass.o
duplicate symbol _OBJC_METACLASS_$_Photo in:
/Users/Kefeng/Library/Developer/Xcode/DerivedData/Photomania-aellrakjngugnzcgrleiytvrfvyt/Build/Intermediates/Photomania.build/Debug-iphonesimulator/Photomania.build/Objects-normal/x86_64/Photo+CoreDataClass.o
duplicate symbol _OBJC_CLASS_$_Photography in:
/Users/Kefeng/Library/Developer/Xcode/DerivedData/Photomania-aellrakjngugnzcgrleiytvrfvyt/Build/Intermediates/Photomania.build/Debug-iphonesimulator/Photomania.build/Objects-normal/x86_64/Photography+CoreDataClass.o
duplicate symbol _OBJC_METACLASS_$_Photography in:
/Users/Kefeng/Library/Developer/Xcode/DerivedData/Photomania-aellrakjngugnzcgrleiytvrfvyt/Build/Intermediates/Photomania.build/Debug-iphonesimulator/Photomania.build/Objects-normal/x86_64/Photography+CoreDataClass.o
ld: 4 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I tried several times by creating new projects and do the same thing. My original intention is to add some custom methods into those to subclasses. But when I add anything into e.g. Photo+CoreData.h/m, the same error as above showed up.
I found some answers about the "double include" or "save files to the wrong directory", but I didn't do that. Anybody have any idea about this?
If you do not generate managed object subclass automatically, then don't forget to check "Codegen" settings for an Entity in Data Model Inspector:
Edit:
Thanks to some help from #iPeter, found the following:
After doing Editor > Generate NSManagedObject files, if you trash the files BEFORE building, your project should build no problems.
Then #import "myManagedObjectName+CoreDataClass.h" (where the MO name is the one in the entity inspector in core data) into any classes where you require those Managed Objects.
In other words, you don't require any of the actual ManagedObject files in your folder. Xcode keeps the generated ones in your Derived Data folder.
If for some reason you need those files to remain in your file directory, the following workaround will work.
Go to your Target and delete the CoreDataClass sources in your Compile Sources.
Leaving you with this:
Most of the new attributes / relationships I added after the initial generation of ManagedObject subclasses were available as properties after a build. In one case where I renamed an existing relationship, I had to do Editor > Generate NSManagedObject Subclasses again, then I trashed the new files in my folder, built, and everything worked OK.
Just wrote a blog post that includes this info for anybody interested.
You should delete all these entities, change "Codegen" settings to "Manual/None" for them in Data Model Inspector, and generate entities again. It works good! You don't need to remove +CoreDataClass.h files from Compile Source. You don't need to mark entities as abstract. You don't need to generate classes by yourself. You should change only "Codegen" settings and regenerate entities automatically.
late post ... but for me was simply a copy paste of an entity, Xcode does not seem to change the original class name associated with the entity (observed on Xcode 9.0.1)
You need to remove the CoreData related sub class generated by yourself, and you can keep the #import line with those classes, now all those files will be generated automatically when build the project.
I recently tried the above answer and it failed.
Somehow, Xcode was still generating the files.
I solved it using the following method:
Mark all entities as Abstract
Build
Remove Abstract flag
Build
Success !
This sounds like a bug in Xcode...
This is the error I'm getting when I try to build my app.
ld: 10 duplicate symbols for architecture arm64
From the error, I would guess that:
you have two files, VaultSelectionViewController.m and SetLockViewController.m (the first being originally a copy of the second, probably)
they both contain #implementation SetLockViewController, and identical properties and/or methods and/or instance variables.
Solution: fix the class name in the #implementation to match the file name.
If that's not the issue, please provide the relevant parts of both files.
Your project twice referring to file SetLockViewController.m.
My suggestion is take a copy of class out side of your project.
[1] Then right click on SetLockViewController.m file and delete > move to trash.
[2] Go to project files directory in finder. Then delete the file SetLockViewController.m (if you find any).
[3] Clean the build and run.
Follow same method if any other duplicate files/linker errors present.
Make sure your compile sources does not have dup files. (Bad merge can cause this issue.) Remove them and add them again can fix this build error.
Make sure you does not implement one function twice. (Copy codes and forget to rename the #implement XXX? Or copy and paste one function twice?) Just search the function define in your project and remove the dup one.
Please check all the variables name in every classes of your project and make sure that all they have unique name including outside the class
I'm currently trying to add LARSAdController to my iOS project with no success.
As soon as i import the files via #import "LARSAdController.h" in my AppDelegate.h the build process fails and on every occurance of (Class)class in LARSAdController.h i get the cryptic error "Expected identifier". BTW I'm using cocoapods.
Example:
- (void)registerAdClass:(Class)class;
which seems fine to me...
If i create a blank project and import the files they compile, so the problem must be in some relation to my code. Anyone got an idea what may cause this?
Thanks for any help in advance!
class is a reserved word in C++, so I would imagine that some of your project uses Objective-C++.
To solve this, use #import LARSAdController.h in Objective-C implementation files only, and remove its use from header files. You can use #class to forward-declare any occurrences of whatever classes are defined in LARSAdController.h in header files (this is best-practise anyway).
If you need to use LARSAdController from an Objective-C++ class then this is more complicated and you will need to use an Objective-C proxy object or modify their header files (which isn't ideal).
There are two situations, that I am aware of, that cause the following errors:
ld: warning: instance method 'resetAudioSystem' in category from /opentok-ios-sdk/Opentok.framework/Opentok(OTPublisher+AudioSnoop.o) conflicts with same method from another category
ld: warning: instance method 'attachAudioSnoopBlock:' in category from /opentok-ios-sdk/Opentok.framework/Opentok(OTPublisher+AudioSnoop.o) conflicts with same method from another category
ld: warning: instance method 'setVideoSnoopDelegate:' in category from /opentok-ios-sdk/Opentok.framework/Opentok(OTPublisher+VideoSnoop.o) conflicts with same method from another category
Possibility 1: A category instance method is declared twice. (Described here: SO)
But, When I do a search of any of the 3 instance methods (in Xcode or Grep) I do not find it declared twice.
Possibility 2: Accidentally importing a .m file. (Described here: SO)
But, I checked all my imports and I only import the framework once in the whole project. Also, only shows up once in Build Phases.
My program runs without crashing, presumably because the last category definition added is used and it happens to be correct. (Source)
Question 1: Is there a way to tell, prior to its addition, where the two categories are located?
Question 2: Any other ideas about how to resolve this?
Note: The Opentok Framework is a binary
Occurs in :
xcode 4.6 & xcode 5
iOS6 & iOS7
I had this warnings because I accidentally imported the implementation file of a category instead of it's header file. So:
wrong: #import 'MyClass+MyCategory.m'
right: #import 'MyClass+MyCategory.h'
I had this error, because I literally pasted my methods' implementation to header file (*.h). It worked well however; the only symptom - warnings.
Check whether your implementation is in correct (*.m) file.
This look like a linker bug. Maybe the SDK got linked more than once, or -ObjC is missing/present where it should not be. Check linker flags. Try deleting all OpenTok frameworks, make sure its missing in your projects, then re-download it and install again.
In my case the header file containing the categories was imported twice for a class.
It wasn't obvious because another header file also imported the same header.
In other words
//Class_with_warnings.h:
#import "Offending_Header.h" // import #1
#import "Class_A.h" // import #2
//Whereas Class_A.h:
#import "Offending_Header.h" // import #2
I have the MvxBindingAttributes.xml in my UI.Droid/Resources/Values but everytime I try to use the bindings in my layouts I get
Warning attribute is not declared.
No resource identifier found for attribute 'MvxBind' in package
'DroidUI'
so for some reason it cannot find those attributes. I have tried to close/reopen/clean/rebuild with no luck, tried removing the layouts and then building (Hoping it would add them at build) and then try to add them again, but nothing seems to work
Have you checked that the MvxBindingAttributes.xml file is marked in properties as an AndroidResource?
VisualStudio likes marking the xml files as content or none instead - especially if you've added the MvxBindingAttributes.xml file as a link.
As an update to this, you can also now use a special 'auto' xml scheme:
xmlns:local="http://schemas.android.com/apk/res-auto"
In the project properties, add a Android Manifest file and add a package name that contains at least two periods, for example:
com.DroidUI
In the axml file, type the package name instead of the namespace:
xmlns:local="http://schemas.android.com/apk/res/com.DroidUI
xmlns:local="http://schemas.android.com/apk/res-auto
Fixed it for me.
First, thanks for the answer. I had the same problem.
But in my case, attempting to use the suggestions above failed. or at least that is what i thought.
When i used local:MvxItemTemplate=#layout/My_Manifest while i had the My_Manifest.axml file correctly placed in Layout folder, and correct xml schemas, it still had problems.
But, when i changed My_Manifest to my_manifest while leaving the actual file name as My_Manifest.axml, everything was working.
just wanted to share
In my case for some reason the MvxBindingAttributes.xml file existed, but hadn't been included in the project. Right-clicking on MvxBindingAttributes.xml and choosing "Include in Project" sorted the problem for me.
Just in case: You might also have rubbish (in my case, it were dots) in some of your XML. But the error pointed "Maybe there's something wrong with the auto-generated XML lol" so it took me half an hour to notice it... Sigh!