Making an app backwards compatible, problems with frameworks - macos

Question

I've been having some trouble making my app backward compatible for Mac OS X 10.6 systems. I've integrated Crashlytics into the app and it works fine for Mac OS X 10.7 - 10.10 and it works just fine. However, the app also needs to be compatible with the older version of OS X 10.6 and the Crashlytics framework only supports down to 10.7.
I already fixed the first crash due to the libc++ library which did not come bundled with 10.6 by making it an optional include. It's the next crash I can't figure out: Symbol not found: _objc_release
If I completely remove all calls to Crashlytics inside the app it works just fine. However, if I include the one line which Crashlytics needs to get started: [Fabric with:#[[Crashlytics class]]]; it will crash right after launching with Symbol not found: _objc_release.
The next logical step for me was to add a simple if statement to check if the system version was compatible with the framework, but the app still crashed although if I removed the Crashlytics line the if statement worked just fine!
I'm using Xcode 7, Mac OS X 10.10 with the base SDK set to 10.6.
Here is a quick example of what I have tried:
Using the suggested way by Apple:
Class cls = NSClassFromString(#"Fabric");
if(!cls)
{
[Fabric with:#[[Crashlytics class]]];
NSLog(#"Framework is installed!");
}
else
{
NSLog(#"Framework is not installed!");
}
Comparing System version numbers:
if(NSAppKitVersionNumber >= NSAppKitVersionNumber10_7)
{
[Fabric with:#[[Crashlytics class]]];
NSLog(#"Framework is installed!");
}
else
{
NSLog(#"Framework is not installed!");
}
Am I missing something obvious here?