Thank you radaee for your reply. I can appreciate the fact that they are different.
However it's the unmodified example code from help_iOS_1.7.pdf and that compilation error doesn't occur in the example project which too has a similar line.
Maybe I'm missing some compilation flag etc.? I did use the -lstdc++ flag. I also double (even triple) checked that I did everything as is instructed in help_iOS_1.7.pdf but I might have misunderstood something.
While I have pretty long programming experience, I am rather new to Objective C.