title: Apple Mach-O Linker (Id) error
body: <p>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.</p>
  
  <p>This happened after I tired implementing a reachability solution I found over <a href="https://stackoverflow.com/questions/3790957/reachability-guide-for-ios-4">here</a> 
  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</p>
  
  <pre><code>-(BOOL)reachable {
      Reachability*r =[Reachability reachabilityWithHostName:@"enbr.co.cc"];
      NetworkStatus internetStatus =[r currentReachabilityStatus];
      if(internetStatus ==NotReachable){
          return NO;
      }
      return YES;}
  </code></pre>
  
  <p>After that I called the function from both of my viwcontrollers viewwillappear methods like so..</p>
  
  <pre><code>- (void)viewWillAppear:(BOOL)animated
  {
      [super viewWillAppear:animated];
  
  
      //-- Check Reachability START ----&gt;
      Reachability *reach = [[Reachability alloc] init];
  
      if ([reach reachable]) {
              NSLog(@"Reachable");
      }
      else {
          NSLog(@"Not Reachable");
      }
       //-- Check Reachability END ----&gt;
  }
  </code></pre>
  
  <p>No errors were produced untill I tried to build and run in the simulator. This is the error I received :(</p>
  
  <blockquote>
    <p>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"</p>
    
    <p>/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/Build/Products/Debug-iphonesimulator/wizcode.app/wizcode</p>
    
    <p>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-ccyrqptvfsabmbahgxartbvxwurq/Build/Intermediates/wizcode.build/Debug-iphonesimulator/wizcode.build/Objects-normal/i386/Reachability-183E2D17A6B26176.o
    for architecture i386</p>
    
    <p>Command
    /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-gcc-4.2
    failed with exit code 1</p>
  </blockquote>