The 2014g to 2014i versions of the tz database incorrectly indicate that "America/Grand_Turk" will be observing AST as of Nov 2, 2014. The 2014j version of the tz database fixes this issue ("America/Grand_Turk" will begin observing AST as of Nov 1, 2015)
This sample project attempts to supply the 2014j tz database to NSTimeZone timeZoneWithName:data: in order to present correctly formatted times (formatted per EST, not AST) after Nov 2, 2014.
As evidenced by the failure of the unit test testAfterSwitchToStandardTimeAttemptingToUseAppSuppliedTimezoneDatabase ignores the 2014j data supplied to NSTimeZone timeZoneWithName:data: and instead just uses the 2014g data that ships with iOS 8.1
That is, NSTimeZone timeZoneWithName:data: does not appear to leverage use the data: parameter.
Either NSTimeZone timeZoneWithName:data: should properly accept and use the data: parameter (providing an error if the data supplied is not usable), or this method (and the related initWithName:data: method) should be deprecated.
Releases of the tz database are available from http://www.iana.org/time-zones