ENOENT error when trying to emulate Ionic made iOS app

I am trying the Ionic framework.Everything ran smoothly but when I tryed to emulate an iOS app

macbook$ sudo ionic emulate ios

I got the following error:

Password:

....

** BUILD SUCCEEDED **

No target specified for emulator. Deploying to iPhone-6 simulator
ENOENT, no such file or directory '/Users/macbook/Library/Logs/CoreSimulator/9F89ED64-0748-4A65-92DF-611110E9D4C4/system.log'
Error code 1 for command: ios-sim with args: launch,/Users/macbook/Documents/workspaceionic/MyTestApp/platforms/ios/build/emulator/MyTestApp.app,--devicetypeid,com.apple.CoreSimulator.SimDeviceType.iPhone-6,--stderr,/Users/macbook/Documents/workspaceionic/MyTestApp/platforms/ios/cordova/console.log,--stdout,/Users/macbook/Documents/workspaceionic/MyTestApp/platforms/ios/cordova/console.log,--exit
Error: /Users/macbook/Documents/workspaceionic/MyTestApp/platforms/ios/cordova/run: Command failed with exit code 2
    at ChildProcess.whenDone (/usr/local/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/superspawn.js:134:23)
    at ChildProcess.EventEmitter.emit (events.js:98:17)
    at maybeClose (child_process.js:735:16)
    at Process.ChildProcess._handle.onexit (child_process.js:802:5)

do you have any ideas about what could be wrong? I'm using Yosemite and Node version is 0.12.7. iOS apps from XCode emulate fine

EDIT: if I open the project with XCode and emulate it, it works.