Several posters are missing the point that of course it's fine to be smiling and pulling faces and gurning for the camera, just not in Iran where they want women to be covered and to stare at the ground.
You're mistaken. The head covering is now enforced more, but young Iranian women are very fashionable, and skinny jeans were de rigeur when I was there eight years ago. And no they don't have to stare at the ground. This is not Afghanistan They are smiley, proud and extremely educated and confident.
I have plenty of photos of me smiling with individuals and groups of Iranian women, all beaming for the camera, too.
This woman smiling in photos will have had no bearing at all on their arrest.