This was an only solution for debugging Ionic apps for me.

emulate.sh

#!/bin/bash
# Manually emulate ionic/cordova application
# Miroslav Masat 2014 

echo "Emulating..."
cd ./platforms/ios/build/emulator
var=$(pwd)

ios-sim launch "$var"/*.app

Same error as @Chener.
Session could not be started: Error Domain=DTiPhoneSimulatorErrorDomain Code=2 "Simulator session timed out." UserInfo=0x7ff8c8c75ab0 {NSLocalizedDescription=Simulator session timed out.}

iOS sim version 8.1 (550.3)
Update: I was able to solve my problem. It was a permission error. I'd created an ionic project using sudo and cause an issue with the files that the simulator was trying to execute (check last response at http://forum.ionicframework.com/t/simulator-session-timed-out-when-ran-ionic-emulate-ios/11437/4). Hope it helps

ionic/cordova emulate ios gets nothing on the simulator, but this tips works !

thank you ......

Thanks, this worked like a charm :)

Thank you very much indeed .! That works for me as well.

Worked, Thanks!