Oh my god, now that's something we don't get to read everyday. OP, are you sure you updated the wallet from a genuine source ?
You should always updated your apps only from playstore/app store and I hope you did the same.
But in that case how can one possible hack your coins. Are you sure you didn't visit any maliciuos website through your phone.
This is another proof that you cannot use a cell phone to store bitcoins. If you like wallets on your cell phone, then you need to use through a hardware wallet. Any software wallet is unreliable and can be hacked. I don't use my mobile phone to store cryptocurrencies at all.
Now I am being a little concerned here because I have my coins stored on a smartphone wallet.
But I am using Mycelium which is an opensource wallet for storing bitcoin and Exodus for altcoins which is partiall open source.
At the same time the phone is completely separate and has no other apps installed. I don't use it for anything at all.