My iphone photo app crashes and deletes all of my pictures?

I got them back because when I reopened the app, it said "restoring…" and after 10 seconds they were all back, but why did this happen?

I have IOS 7

It's a faulty app, had one of those before. The makers didn't make it properly. It sucks. I'd suggest get a new one like PicsArt.

All software and application have some exception and sometime they are not able to find what they want to do and stuck with their program at any time and OS display app crashed (due to not able to find program what it want to execute.) for more technical guidance follow http://www.machealthcheck.com/mac/mac-support.html.