Xcode4 Linking Problem. File was built for archive which is not the architecture being linked (arm6)

Question

Recently, I switched to Xcode4 and when I compile my project I got following error.

ld: warning: ignoring file /Users/myname/Library/Developer/Xcode/DerivedData/appname-hezrgyqimckztgbdlslkavphdclw/Build/Products/Debug-iphoneos/libTapkuLibrary.a, file was built for archive which is not the architecture being linked (armv6)
Undefined symbols for architecture armv6:
  "_OBJC_CLASS_$_TKLoadingView", referenced from:
      objc-class-ref in RootViewController.o

I opened the TapkuLibrary and checked that it's Architectures set to 'Standard (armv6 armv7)'.

What can I do to fix this problem?

Answer 1

I figured out what caused the problem. I changed 'Build Active Architecture Only' of TapkuLibrary from Yes to No and it compiles with no problem.