Viber update

Hello there! Yesterday this happened:

i started receiving these alerts via my calendar app, that my iPhone was being hacked and i need to update my viber which i did through my app store but the alerts still continued, ive restarted my phone, deleted both apps viber and calendar but i still get these messages and it says that ive visited porn websites which i did not and got viruses on my phone. I want to ask is it possible and usual for iphone to get viruses/hacked and if not, what the ****

is that ****? And im being alarmed evert hour so its getting pretty annoying. Im attaching a screenshot although it is in Bulgarian but if it is helpful to you.... i would be glad if you contact me back. Thanks in advance!

Best regards,

Ivona Georgieva