I know there are several posts on this already… just wanna raise attension 
tried appium 1.5.3 and xcode 7.3.1, ios 9.2, does not work…
IWD is pretty critical piece for the performance, without it, two time s slow.
appium dev, please help on this, or confirm us if it is supported or not for xcode7.3.1 and appium 1.5.3, thanks
No - not out of the box but there’s an easy fix for it.
There was an issue with IWD which was reported and fixed by @Russ and this fix got recently merged into the Appium sources.
I applied the patch to xcode-iwd.sh myself on an installed 1.5.3 release version and re-ran the script. IWD is working fine for me since then with Xcode 7.3.1