_OBJC_CLASS_$_ - symbol(s) not found error

I create a new application for iPad starting from an UISplitView 开发者_StackOverflowapplication that works correctly, in the new application I get this error:

"_OBJC_CLASS_$_ConcertListController", referenced from:
objc-class-ref-to-ConcertListController in RootViewController.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

What it mean? How can I solve?

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Apparently you need to link in whatever framework ConcertListController is a part of. Try going to the project window, right click on frameworks and choose add existing framework .... you should be able to find the framework including ConcertListController there.

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I also had a similar problem. My solution was remove the reference and re added those files. Then it will show a window and make sure to tick on "Add to target" check box.