Tried to fly my spark and my iPhone screen kept going black. It has never done this before. Any ideas?

Brian, any error message from the app? Please try to change a mobile device. I would recommend you save all the file in the app and then reinstall it. Please keep us updated, thanks.

I turned off the iPhone and restarted it. I flew it several hours later at a different location and no issues. And as usual, had a great time flying & got some nice pics.