Does putting your iPhone in the sun increase or decrease my battery life?

I heard it charges it, but I heard it really messes up battery life. Which one is true?

It would mess it up because it will increase the discharge rate, decreasing your battery life.

If you have a solar charger it will do both at the same time, but if you don't it will just mess it up

It won't do any good, and may damage the screen or camera sensor. Don't do it.

Why would anyone expose it to extreme heat or cold? Thats just stupid.