SIGABRT or an EXC_BAD_INSTRUCTION usually means the app crashed itself intentionally because some check failed. These should log a message to the debugger console with more information; check there for more information.
SIGABRTs are caused by uncaught Objective-C exceptions. There are a lot of reasons exceptions can be thrown, and they will always log a lot of helpful information to the console.
NSInvalidArgumentException, which means the app passed an invalid argument to a method
NSRangeException, which means the app tried to access an out-of-bounds index of an object such as an
NSInternalInconsistencyExceptionmeans an object discovered it was in an unexpected state.
NSUnknownKeyExceptionusually means you have a bad connection in an XIB. Try some of the answers to this question.