Where are iOS simulator screenshots stored?

They get saved to the Desktop, look for a PNG file with the naming convention "iOS Simulator Screen shot [DATE].png"

1. If you create screenshots from within the simulator using File -> Save Screen Shot (Command-S), those files end up on the Desktop as something like: iOS Simulator Screen shot Apr 22, 2012.png.

2. Under Xcode 6 & newer, device screenshots taken with the "Take Screenshot" button in the Xcode "Devices" menu will end up on the desktop. Look for a file named "Screen Shot 2014-MM-DD at HH.MM.SS.png"

3. For Xcode 5 & older, if you create screenshots from within Xcode (Organizer), you'll find these in ~/Library/Application Support/Developer/Shared/Xcode/Screenshots. To take screenshots from the Xcode (Organizer) you need to have hardware device attached. The organizer does not appear to take screenshots from the simulator.

And outside of Xcode:

1. If you create screenshots using the Finder (command-shift-3 or command-shift-4), these also end up on the Desktop as something like: "Screen Shot 2012-04-22 at _ AM.png"

2. If you use the Grab application (found in /Application/Utilities), you can save those files anywhere you decide. :-)

3. If you have saved a screenshot to the Photos library from within your app, for example with UIGetScreenImage and UIImageWriteToSavedPhotosAlbum, they end up at ~/Library/Application Support/iPhone Simulator/***version***/Media/DCIM/100APPLE

With Xcode 9+, Simulator saves screen shot file on (logged-in user's) Desktop and it's default path.

To change default path (with Xcode 9+), press and hold ⌥ Option (alt) button from keyboard, while you take a screen shot. It will show to a dialog with file storage options and also allows to set/change default path.