A new update has come out for pocket edition! It adds a simple version of normal survival!

Survival Update
New Game Modes
Creative
You can fly. Press up or down arrows twice to ascend/descend (Press the jump button twice) to go higher double press and hold forward button(when floating when moving you can not).
Survival
Crafting is still not an available feature.
The Day/Night cycle has been introduced.
Even though it is Survival, the user can still see the blocks as though he were Creative mode, but he cannot use them unless he has gathered some of this material.
This effectively works as the Inventory.
Stone tools are the only type of tool, and it has an infinite amount of durability.
When breaking materials, you can gather any material regardless of what is used.
For example, you can now break stone with your hand and receive cobblestone, but using a pickaxe is still faster.
New Mobs
Sheep
Zombie
New Blocks
Fence
Fence Gate
Wooden Door
Cactus
Oak wood is unobtainable and trees now spawn with Dark wood
New Tools
Stone Shovel
Stone Pickaxe
Stone Axe
Stone Sword
Shears
To shear a sheep, you must touch and hold down on the screen, similar to breaking a block. If you do not, you will simply hurt the sheep and eventually kill it (8 hits).
Bugs:
When attempting to type in a seed, the virtual keyboard covers up the box you type the seed into and you cannot see what you are typing.
White wool is unobtainable.
There is no way to get stone blocks in Survival. (Possibly not a bug, but intended as there is no crafting yet.)
You can not see the fire when the zombies burning in the day light.
You can hit mobs through glass.
You can not see fence gates when they are selected.
You can hit mobs through doors when looking through the window part of the door.
Sugar cane is unobtainable in survival.