Stuck on grey screen

After upgrading from the previous beta version, I am stucked on a Grey screen, just after the mojang red screen, and never gets the loding bar. Restarting the mobile Phone des not help. The o.ly way That I found is to uninstall minecraft, and reinstall it. Doing that I can lunch it straight. I have lost my worlds (unsure if his is à normal behaviour), but I can play.

Anyway, after à while like  jumping to another application, and going back to minecraft (whatever I Smith back or relaunch it, I face the grey screen again... and can wait hours without any  succession.

Please help