Missing appointment dates on calendar, could be due to suspicious pop up on iPhone?

319Nanny wrote:

All saved appointment that were set up on iPhone are now gone.

Recently received pop up days from Apple about iPhone being hijacked malware or something and I needed to click but I didn’t . I just ignored. Would apple ever send message saying iPhone was hacked, hijacked or whatever ?

[Re-Titled by Moderator]

No, as there are no known virus/malware/spyware/hack for a non jailbroken phone.