CODEWITHSUNDEEP
iphoneobjective-c
cmltkt
cmltkt

Reputation: 193

Apple O-mach linker error

I created a NSObject file with name "ObjCWorkAppMath.m", it contains some useful functions and I want to use that class in my ViewController file but XCode doesn't compile my project and returns the error below:

duplicate symbol _OBJC_METACLASS_$_ObjCWorkAppMath in:
    /Users/ctkt/Library/Developer/Xcode/DerivedData/ObjCWorkApp-hgxcjtjhzwxhqxcmxgkpucpfpieq/Build/Intermediates/ObjCWorkApp.build/Debug-iphonesimulator/ObjCWorkApp.build/Objects-normal/i386/ObjCWorkAppMath.o
    /Users/ctkt/Library/Developer/Xcode/DerivedData/ObjCWorkApp-hgxcjtjhzwxhqxcmxgkpucpfpieq/Build/Intermediates/ObjCWorkApp.build/Debug-iphonesimulator/ObjCWorkApp.build/Objects-normal/i386/ObjCWorkAppViewController.o
duplicate symbol _OBJC_CLASS_$_ObjCWorkAppMath in:
    /Users/ctkt/Library/Developer/Xcode/DerivedData/ObjCWorkApp-hgxcjtjhzwxhqxcmxgkpucpfpieq/Build/Intermediates/ObjCWorkApp.build/Debug-iphonesimulator/ObjCWorkApp.build/Objects-normal/i386/ObjCWorkAppMath.o
    /Users/ctkt/Library/Developer/Xcode/DerivedData/ObjCWorkApp-hgxcjtjhzwxhqxcmxgkpucpfpieq/Build/Intermediates/ObjCWorkApp.build/Debug-iphonesimulator/ObjCWorkApp.build/Objects-normal/i386/ObjCWorkAppViewController.o
ld: 2 duplicate symbols for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I tried all solutions in stackoverflow for this error and it still doesn't work or I can't do it right...

#import "ObjCWorkAppViewController.h"
#import "ObjCWorkAppMath.m"

@interface ObjCWorkAppViewController ()

@end

@implementation ObjCWorkAppViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Where is the mistake?

Upvotes: 0

Views: 151

Answers (1)

Martin R
Martin R

Reputation: 540055

Replace 

#import "ObjCWorkAppMath.m"

by

#import "ObjCWorkAppMath.h"

Importing the implementation file instead of the interface file causes the class to be defined twice: In "ObjCWorkAppMath.m" (where it belongs), and in "ObjCWorkAppViewController.m" (which is not intended).

Upvotes: 2

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