iPhone hacked but seems to be working

What makes you think your iPhone was hacked yesterday? If you received a message that your phone was hacked, just delete and move on with your day, nothing was done to your phone. If you inadvertently responded to a message and provided your Apple Account/Password, then it is likely your account would have been compromised, but not that your phone is hacked. If that was the case, then you need to change your Apple Account password.

Your phone was not hacked yesterday or at any time before that. It will not be hacked at any time in the future as long as you do not jailbreak your phone.

Think about it. If someone really was smart enough to hack your phone, they would never be dumb enough to leave any trace that they did.

Your phone did not get hacked yesterday, or ever for that matter.

Why do you think it was?