Entering website pushes notification on iPhone

I want to make a Simple App. I’m a beginner in Swift, with Just basic knowledge, But I’m Very Good at PHP and JS, So basically, programming is not foreign to me.

The App should cowork with my website and it should do Only one thing. When person visits my web, I get a notification on my iPhone. Simple as that, yet I have no idea how to make it.

Any ideas, recommendations?

Any help Appreciated.

Thanks.

Dave