Why won't snapchat open?

I've got a iPhone 4, running iOS 7.0.1

I recently updated snapchat, and now I come to use it. it won't open.

I tap on the icon on my home screen, and it fades/goes darker as if it's going to open, then after a few seconds the icon just returns to it's usual brightness, the app fails to open up. I have updated it again since it first started happening, and it is still doing the same thing.

Any ways of resolving this so I can carry on using snap chat?

Thank you in advance.