voltage input for iphone

The charger you put into the wall will handle the outlet voltage. This voltage depends on where you live. E.g., in Europe you have 220 V, in the US you got 120 V. This has nothing to do with the iPhone or any device you want to charge.

This is due to the power brick, the one you plug in your outlet, which regulates the output voltage for your iPhone to 5 V.

You can't charge an iPhone with say 120 V!

That's basically the reason, why a lightning cable hasn't got just two contacts to plug directly into your wall. This would fry your device!

iPhone can accept the voltage of any country. If you are in the US, it would 110v. If you are in another country, which is 230v, it will accept that. All one has to be cognizant of is to use a wall plug appropriate to the country the phone will be used in.

It takes 5 Volts to charge.