iOS simulator always saves images on desktop
[Edit to add Automator steps]

You can't change the location, but I often use a little script like this to keep things tidy:

#!/usr/bin/env bash

destination=~/screenshots

while [ true ]; do
    if [ -n "$(shopt -s nullglob; echo ~/Desktop/Simulator\ Screen\ Shot*.png)" ]; then
        mv -v ~/Desktop/Simulator\ Screen\ Shot*.png "$destination";
    fi
    sleep 5
done


Since you're using the iOS simulator you probably know how to create this as an executable script already, so I'll avoid giving those instructions.

If not, I might use Automator.


Create folder screenshots in your home directory
Start Automator and create a new Document of type Application
Find the Run Shell Script action and drag it from the actions on the left to the workspace on the right
Paste the shell script without the first line with #! stuff
Save it and run it from applications
You should see the screen shot files be moved.
Here's a visual. http://www.screencast.com/t/KEbAFifHCTcc