How to check if a static library is built for 64-bit?

I just built a static library for iOS with the build setting for Architectures set to $(ARCHS_STANDARD_INCLUDING_64_BIT).

I want to make sure that the .a library is properly including that architecture, but when i run lipo -info on it, I see:

Architectures in the fat file: library.a are: armv7 armv7s (cputype (16777228) cpusubtype (0))

Does this mean that arm64 isn't included? If the lipo command can't tell me, is there another way to tell?

I'm running Xcode 5 with the latest Command Line Tools installed.

Yes, an arm64 slice is there. To see it, you need to use lipo from the iOS toolchain, not from the host system (which doesn’t know about arm64):

xcrun -sdk iphoneos lipo -info $(FILENAME)

good old file can do the trick, too:

$ file libTestFlight.a

libTestFlight.a: Mach-O universal binary with 5 architectures
libTestFlight.a (for architecture armv7):   current ar archive random library
libTestFlight.a (for architecture armv7s):  current ar archive random library
libTestFlight.a (for architecture i386):    current ar archive random library
libTestFlight.a (for architecture x86_64):  current ar archive random library
libTestFlight.a (for architecture cputype (16777228) cpusubtype (0)):   current ar archive random library

It seems that nobody at Apple cared to add the arm64 cputype to file, yet.

Interestingly, in the iOS 7 Tech Talk Videos ("Architecting Modern Apps, Part 2", PDF page 35) they show a working file tool's output: