title: Undefined symbols for architecture armv7, ld: symbol(s) not found for architecture armv7 - what to do?
body: <p>I've read many posts on SO and none of the proposed solutions are working for me. I'm hoping someone who knows a little more about interpreting errors can help.</p>
  
  <p>My app has been working fine (and still does), but I'm having an issue when using a certain class 'iCarousel' which is an implementation of Cover Flow.</p>
  
  <p>Here's the interesting thing: When opening the sample project for the iCarousel, it runs fine on my iPhone. My app (in a separate project) also runs fine. They are both using <code>armv6 armv7</code>  architectures and running on iOS 5.1.</p>
  
  <p>I then copy the class to my own project and add all necessary frameworks. There are no errors yet. But when I build and run I get an error:</p>
  
  <pre><code>Ld /Users/Sooper/Library/Developer/Xcode/DerivedData/TestApp-
  ejfsezvwxyxhqpanwwrcmsbkslxi/Build/Intermediates/TestApp.build/Debug-
  iphoneos/TestApp.build/Objects-normal/armv7/TestApp normal armv7
  
      cd "/Users/Sooper/Developer/TestApp v1.0"
      setenv IPHONEOS_DEPLOYMENT_TARGET 5.0
      setenv PATH "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin:
      /Applications/Xcode.app/Contents/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
  
  /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -arch armv7 -isysroot 
  
  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS5.1.sdk
   -L/Users/Sooper/Library/Developer/Xcode/DerivedData/TestApp-ejfsezvwxyxhqpanwwrcmsbkslxi/Build/Products/
  Debug-iphoneos -F/Users/Sooper/Library/Developer/Xcode/DerivedData/TestApp-ejfsezvwxyxhqpanwwrcmsbkslxi/Build/Products/
  Debug-iphoneos -filelist /Users/Sooper/Library/Developer/Xcode/DerivedData/TestApp-ejfsezvwxyxhqpanwwrcmsbkslxi/Build/Intermediates/TestApp.build/
  Debug-iphoneos/TestApp.build/Objects-normal/armv7/TestApp.LinkFileList -dead_strip -miphoneos-
  version-min=5.0 -lz -framework QuartzCore -framework CoreGraphics -framework 
  SystemConfiguration -lxml2.2.7.3 -framework Security -framework CoreMedia -framework Accounts 
  -framework CoreFoundation -framework AudioToolbox -framework AVFoundation -framework Twitter -
  framework MediaPlayer -framework UIKit -framework Foundation -o 
  /Users/Sooper/Library/Developer/Xcode/DerivedData/TestApp-
  ejfsezvwxyxhqpanwwrcmsbkslxi/Build/Intermediates/TestApp.build/Debug-
  iphoneos/TestApp.build/Objects-normal/armv7/TestApp
  </code></pre>
  
  <p>Under this:</p>
  
  <pre><code>Undefined symbols for architecture armv7:
    "_OBJC_CLASS_$_ArtworkScrollerViewController", referenced from:
        objc-class-ref in TestAppViewController.o
  ld: symbol(s) not found for architecture armv7
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>If I remove the instance of the class the error goes away and the app runs. I'm totally confused. Why would it work separately but not in another project?</p>
  
  <p>Would greatly appreciate some guidance.</p>