If you ever get the following error:

“Internal Error
File: /SourceCache/IndigoDebuggingPlugin/IndigoDebuggingPlugin-31/IndigoDevice/XCiPhoneSimulatorDevice.m
Line: 265
Object:
Method: _launchSimulatedExecutable:

Assertion failed: nil == _currentSimulatorSession"

I’ll save you about 2 hours of your time. There are some complicated solutions to this problem (here). But all you need to do is, quit xcode/iphone simulator, go into your (username)/Library/Application Support/ and delete the iPhone Simulator folder. Restart xcode and build your app. Worked for me. So pissed that wasted 2 hours of my life.