I am pretty sure that you can see this in the OS X Console app located in Utilities. If I'm wrong though, be sure to vote me the heck down so I delete this.
UPDATE:
Specifically (as of OSX 10.11.6),
When an app crashes on emulator, a subfolder (with a unique id) is added to:
~/Library/Logs/CoreSimulator
Within that, start by examining stderr.log and system.log.
When the emulator itself crashes, a subfolder is added to:
~/Library/Logs/DiagnosticReports
Don't confuse this path with
/Library/Logs
(lacking ~ at start), which has different reports about your mac.
The console will show the NSLog() output from an app running in the simulator. The crash logs are saved to file.
I have found some in my home directory under
~/Library/Logs/DiagnosticReports/
They have a file extension of .crash
Something I haven't yet figured out is how to get them to generate even if the debugger grabs the EXC_BAD_ACCESS signal.
Update
Currently, (OSX 10.11.6), the .crash logs in ~/Library/Logs/DiagnosticReports, are when the emulator itself crashes. Logs for an app crashing (but the emulator device is still running fine), are in:
~/Library/Logs/CoreSimulator
Per crash, there is a sub-folder with a unique id. Sort by date, so that your recent crash is the first sub-folder. Inside that, start by looking at stderr.log and system.log.
Also directly under CoreSimulator, see CoreSimulator.log and Simulator.log.
Here’s something that worked for me in a special case... My app was crashing with SIGKILL as it terminated. I would see the exception in main.m for a few seconds, and then the app would finish terminating – thus, no chance to get the back trace.
I did a lot of searching on “where does simulator store its crash logs” and never managed to find an answer. However, the following trick came in quite handy and I was able to grab the crash log on the fly:
Basically, open /Applications/Utilities/CrashReporterPrefs.app and change the setting to “Developer”. This will cause CrashReporter to display a popup with the crash log after your app crashes.
For me, it was an expression that I had added to the debugger watch window. When a breakpoint was getting hit, the bad expression was causing XCode to segfault.
None of the answers above worked on the "Big Sur" OS version. The only way to find the log was through the "Console" app (Application/Utilities/Console)