i.e. does this call:
NSString *udid = [UIDevice currentDevice].uniqueIdentifier;
return always the same UDID when it is executed on the iPhone Simulator on any mac computer or not?
Currently the iPhone Simulator on my computer returns "2BA99337-3AE2-5234-93DA-193703B876F8".
My UDID is reporting as 03B41D62-FB69-5B6D-A95E-473842F4DFE3 from the iPhone Simulator, so it looks like you're correct.
The UDID of the simulator is actually the same as the UDID of your Mac. You can easily verify this by looking at the System Profiler utility (where it is called the Hardware UUID).
On iPhones, iPads and iPod Touches, it is 40 lowercase hex digits, probably a SHA1 hash of some hardware identifier.
Xcode has this data for you:
- Xcode 5: Open Organizer
- Click My Mac
Look at the Identifier for the machine there.
-OR-
Xcode 6: Open Devices (CMD+SHIFT+2 -OR- Window -> Devices)
- Click the simulator you're running
- Look at the Identifier for the simulator there
Open terminal and type in system_profiler SPHardwareDataType - the output under Hardware UUID is the ID used for all instances of iOS simulator running on that specific computer.
来源：https://stackoverflow.com/questions/1520189/is-the-iphone-simulator-udid-unique-for-each-installed-instance