My sister and I generated a Minecraft PE world. I have looked around, and there are no cows or pigs anywhere in the map! I really need milk, is there any way I can make them spawn?
You need to be in a plains or forest biome in order for them to spawn, a rain forest biome doesn't work. If you are looking at a desperate resource for milk you can always use spawn eggs to bring in cows and pigs.
If you're on survival then I'm afraid that you can't spawn them easily. I've heard that you create a large room then put fences around inside the room, cover the floor with torches then they should spawn. But I don't think it works(I haven't tried). The way I do it is make a world on creative, choose the cow egg, touch the ground where you want the cow then go to the chat and type in /survival. Once you've done that you'll need to make a bucket then hold it on the cow for a second, your bucket should automatically become a milk bucket. Hope that this helps!
You could just download something such as Plug Pe and get commands but if you don't then you could just get out of the world and change it to creative mode go back spawn cow go back etc.