According to these comments, JSONKit does not support ARC, and not even running with fobjc-no-arc setting in an ARC environment: https://github.com/johnezang/JSONKit/issues/37
You can still use JSONKit in your application with ARC.
I'm using it myself.
Select your project root in XCode 5, under Targets
select your application then select the BuildPhases
tab. Under Compile Sources
double-click JSONKit.m and add the following compiler flags -fno-objc-arc
.
Hope it helps
Cheers