Is ICU considered to be a private framework in Apple terms? It’s not very clear to me whether the header files in $SDK/usr/include/ are private or not. I’d like to use functions like u_strcasecmp from <unicode/ustring.h>.
The header files are present so I make an assumption that it’s not really private. On the other hand I cannot find Apple documenting any ICU functions in their API reference.
All frameworks not described in Apple reference and invisible in header files can be considered as ‘Private’ (hence not usable in an AppStore application).
All framework/method references present in headers but not in Apple reference documentation are considered ‘Undocumented’, and should not be used in AppStore apps (but sometimes, it does the trick…)