How to change Minecraft PE world from creative to survival in 0.9.0?

So I definitely know how to change worlds from creative to survival back when there was only the 0.8.1 update. But now that the 0.9.0 came out, when I try to change my world, it seems all different - I opened up iExplorer, opened up my world folder, but I don't see the chunks.dat or the entities.dat. The only thing I saw was the level.dat. I successfully changed my world, but for some reason I was able to fly in survival and mobs weren't able to hurt me, I didn't want that.