How to turn a creative seed into a survival seed in minecraft pocket edition?

I have created a really good seed in MinecraftPE. But it was a creative seed. Now I want to use it as a survival seed but I don't know how. Any idea?

Seeds work for both gamemodes…

Unless you mean world. If you are trying to turn a creative world into a survival one, you can't.

If you get the new update you go to the pencil to the right of your world's click on it at the bottom you can switch it from survival to creative there and none of your stuff on that world is deleted