I do think she probably only just found it. It is highly likely she only wanted to look at it, keep it for a while to explore what iPhones can really do. Obviously wrong, but to her mind she had no intention of stealing it, it was just there so she picked it up.
We had a similar thing with difficult child 1 - he found a watch on the ground. He wanted to give it to his girlfriend, I said that was not right because it was not his to give. But he couldn't afford to buy her anything, he whined. This of course was because he had been stealing cash from me about six months earlier and had lost his allowance until it was paid back.
So what we did - I went with him to hand the watch in to police. I stayed present while difficult child 1 explained where he found it, when, gave all details. I was confident he was being truthful, because I've generally known when he was lying. The policeman then explained to difficult child 1 that he had done a good thing ini handing it in, and if nobody reported it missing or claimed the watch after three months, they would give it to him.
And they did. Three months later we got a phone call; could we come by and pick up the watch?
difficult child 1 was very happy - he had done the right thing after all, and he did give it to his girlfriend. But when he did, it was his to give at last.
It was a very valuable lesson.
I wouldn't punish her too hard (other than loss of your trust), just involve her in the process of returning the iPhone. Have her either make the phone call, or sit with you while you do it. Have her hand it over to the owner. If he realises she accessed porn on his phone - good! Serves him right for keeping porn on his iPhone when he works with kids.
Any embarrassment etc - she has to wear it. Don't YOU worry about your daughter's reputation here, other than how other people see her. It's got nothing to do with how people see you. Anyone who doesn't get that - their opinion doesn't matter.
The aim is to prevent a recurrence. Better yet, to teach her by example and modelling, the right way to behave in this situation. Teach. Not punish into teaching. You could even ask her, if you feel she needs to be punished, what she feels an appropriate punishment would be. But frankly, getting caught and having to follow through and hand it back in person will be particularly galling, especially since she beat his high score on the game when she only had the phone a few hours. Her high score will be on his phone and he will know. And she will know he knows. She has to live with that - she left a trail on his phone. That also will be embarrassing for her. Good. If she had come to you right away and worked with you to find the owner, she would not be embarrassed. She might even be up for a reward!
by the way, if he offers her a reward, let him. It will make her feel even more uncomfortable. Coach her to refuse the reward because she GOT her reward - playing the game. But if he knows this and insists - let him. Then quietly tell her later, "You would be enjoying the reward a whole lot more, you would feel a lot better about it, if you had done the right thing to begin with. Next time, you know what to do."
This could be a very valuable lesson on so many fronts, if you involve her in doing the right thing. She would probably prefer the punishments!
Marg