Apple Mach-O Linker (Id) 错误

Question

Got this error for the first time, I have looked around and cannot find a solution to help me, I have cleaned my build and also checked to make sure I am compiling for the latest firmware.

This happened after I tired implementing a reachability solution I found over here I imported the two reachability files (.m/.h) then added this code into the.m file and delared t in the. h of the reachability files

-(BOOL)reachable {
    Reachability*r =[Reachability reachabilityWithHostName:@"enbr.co.cc"];
    NetworkStatus internetStatus =[r currentReachabilityStatus];
    if(internetStatus ==NotReachable){
        return NO;
    }
    return YES;}

After that I called the function from both of my viwcontrollers viewwillappear methods like so..

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];


    //-- Check Reachability START ---->
    Reachability *reach = [[Reachability alloc] init];

    if ([reach reachable]) {
            NSLog(@"Reachable");
    }
    else {
        NSLog(@"Not Reachable");
    }
     //-- Check Reachability END ---->
}

No errors were produced untill I tried to build and run in the simulator. This is the error I received:(

Ld /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Products/Debug-iphonesimulator/wizcode.app/wizcode normal i386 cd "/Users/imac/Documents/Iphone applications/wizsanCode/wizsanCode.5/wizcode" setenv MACOSX_DEPLOYMENT_TARGET 10.6 setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"

/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-gcc-4.2 -arch i386 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk -L/Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Products/Debug-iphonesimulator -F/Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Products/Debug-iphonesimulator -filelist /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Intermediates/wizcode.build/Debug-iphonesimulator/wizcode.build/Objects-normal/i386/wizcode.LinkFileList -mmacosx-version-min=10.6 -Xlinker -objc_abi_version -Xlinker 2 -lz -framework CoreGraphics -framework MobileCoreServices -framework SystemConfiguration -framework CFNetwork -framework UIKit -framework Foundation -o /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Bui ld/Products/Debug-iphonesimulator/wizcode.app/wizcode

ld: duplicate symbol _OBJC_IVAR_$_Reachability.reachabilityRef in /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Intermediates/wizcode.build/Debug-iphonesimulator/wizcode.build/Objects-normal/i386/Reachability-183E2D17A6B26176.o and /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Intermediates/wizcode.build/Debug-iphonesimulator/wizcode.build/Objects-normal/i386/Reachability-183E2D17A6B26176.o for architecture i386 collect2: ld returned 1 exit status Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-gcc-4.2 failed with exit code 1 ld: duplicate symbol _OBJC_IVAR_$_Reachability.reachabilityRef in /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbahgxartbvxwurq/Build/Intermediates/wizcode.build/Debug-iphonesimulator/wizcode.build/Objects-normal/i386/Reachability-183E2D17A6B26176.o and /Users/imac/Library/Developer/Xcode/DerivedData/wizcode-ccyrqptvfsabmbah gxartbvxwurq/Build/Intermediates/wizcode.build/Debug-iphonesimulator/wizcode.build/Objects-normal/i386/Reachability-183E2D17A6B26176.o for architecture i386

Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-gcc-4.2 failed with exit code 1

Answer 1

So, the problem has been resolved.

What happened was when I imported the reachability files over into my build something funny was happening and somehow I deleted the reachability files that were already in my build being used by the "all seeing I" ASIHTTPRequest methods I was using for transporting my data... which messed everything up.

So long story short I replaced the files and everything is working fine and I also found out that ASIHTTPTequest is taking care of the reachability for me:) how cool is that.

Answer 2

Check if SystemConfiguration is linked properly. Anyway, clean up your code:

+ (BOOL)reachable {
    Reachability *r = [Reachability reachabilityWithHostName:@"enbr.co.cc"];
    NetworkStatus internetStatus = [r currentReachabilityStatus];
    return internetStatus != NotReachable;
}

And then just call [Reachability reachable] wherever you need. This also fixes a memory leak you have.

Answer 3

Just to add to this, it happened me after I regenerated managed subclasses and it didn't actually overwrite the existing ones but just made new duplicates. I just deleted both and regenerated and it was all good.

Answer 4

Remove it then add it again. Works for me. :D

Answer 5

This happens with me when i am adding third party analytics framework in my project. When i check with the info of framework its not properly copied on disk. i download new framework and copied it into project and now there is no error.

Answer 6

I had this code in one of my UIViewController and removing it solved this bug. What a stupid and not-clear-at-all error message

NS_ENUM(NSInteger, Mode) {
    Assessments = 0,
    Onboarding
};

Answer 7

Make sure you are running YourApp.xcworkspace instead of.xcodeproj file. I did face the same issue when did run.xcodeproj file. Running.xcworkspace has solved the problem and the error has gone away.

Answer 8

After modifying my core data model, I deleted all the (auto generated) NSManagedObjectModel subclasses, and created them again. Once they all were created, I dragged them to a Group folder in XCode... and got the spinning beachball for longer than usual.

The next time I tried to run, it failed with the "Mach-O-Linker" (Id) Error. After reading other responses, I figured it might have something to do with the NSMObj classes not being where expected. I deleted them, quit, opened, generated them, and put them in their customary group folder... and Viola. no Mach-O error.

I see that the problem is resolved, but I post this just to index it under the proper question. In my case, deleting and regenerating (via editor menu) the managed object subclasses fixed the issue.