iOS Simulator 7.1 crash running on Yosemite with weak linked new frameworks (Symbol not found: _objc_isAuto)

Question

I have just updated to xCode 6.1 and had to reinstall my iOS 7 simulators.

I can run my app on all the simulators apart from the 5s iOS 7.1 sim. I get this crash

dyld: Symbol not found: _objc_isAuto
  Referenced from: /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
  Expected in: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.1.sdk/usr/lib/libobjc.A.dylib
 in /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
(lldb) 

What gives? Any ideas why this sim crashes?

Thanks

Answer 1

This issue can occur if you are building your project against the iOS 8.x SDKs and are weak linking a framework that is new to iOS 8.x and also present in OS X 10.10 and you run in the iOS 7.1 simulator.

The Xcode 6.1 Release Notes mention this issue:

If an app is weak linked against frameworks new in iOS 8 SDK and OS X 10.10 SDK, it may fail to run if the run destination is an iOS Simulator for older iOS runtimes and the host system is running OS X Yosemite. (17807439)

The issue is resolved in the updates iOS 7.1 simulator runtime that can be downloaded from Xcode 6.2 beta 4 an later (and I think possibly beta3 worked as well).