@Gunner thanks a lot for that explanation. And you are completely right: it is totally confusing if you select a sketch in the example browser for a certain hardware and than it does not work for that hardware… So a hint in the example browser would be really helpful…
My intention by using the example was to see how I have to work with the terminal widget in combination with my BananaPi.
Since I have already that Using C++ on a Raspberry Pi with Blynk example up and running for me the question is more: how could I use the terminal widget on the BananaPi? Is there a documentation how I can output something from the Banana to the terminal widget on my iPhone? Why does the compiler brings up the above mentioned error? What do I have to use instead of println?
Or is the terminal widget in general not usable with a PI (if necessary I would also set up a Raspberry Pi)?
Thank you so much for your help!