Custom fonts on iOS app using AIR 3.9

we are building an app for iOS using AIR 3.9 where we have to display the text using different fonts which are not available on iOS 5 or later. To fix this issue we have found a solution using XCode via ANE where by using "CTFontManagerRegisterGraphicsFont" class we can download the font from a location and register it on the device(working on mac using simulator ).  But when we are packaging the ANE with AIR 3.9, it gives us the error which says that:-

Error occurred while packaging the application:

Undefined symbols for architecture armv7:

  "_CTFontManagerRegisterGraphicsFont", referenced from:

      ___setPath_block_invoke in libnet.example.download.a(IOSFontLib.o)

ld: symbol(s) not found for architecture armv7

Compilation failed while executing : ld64

can anyone suggest where we are going wrong!

thanks in advance