which iOS SDK version are you using? To make sure that you have implemented the right delegate method, open the WTArchitectView.h file (either by selecing it from the .framework in Xcode or by cmd+click on the header include) and have a look at the WTArchitectViewDelegate protocol definition. Copy and paste the invokedURL method declaration into your project.
If you set the delegate of your WTArchitectView instance in -viewWillAppear:, you could set a breakpoint in e.g. -viewDidAppear: and check if the correct object is set as the delegate.