I need to do some moonrise azimuth and time calculations. Can anyone recommend a good astronomy library, preferably in Objective-C?
I recommend PJ Naughter's AA+ library. It is based on the Astronomical Algorithms book by Meeus. The library is quite comprehensive and written in C++ (easily called from Objective-C). My iOS app Lúan uses this library.
Maybe code of opensource projects could fit you? Recently on FLOSS-Weekly was a discussion about Stellarium.
Disclaimer: I didn't look at that source of Stellarium so I have no idea if it is useful at all and unfortunately it is written in C/C++.
Its not in objective C but the library included in the pyephem package is quite good. The C source files were taken from the old X windows xephem program with glue added to make the functions available from within Python. As long as you don't require super-high accuracy, these routines will probably work for you.
For those still interested in 2016, I've made an Objective-C(++) and Swift wrapper around PJ Naughter's AA+ library. It is based on the Astronomical Algorithms book by Jean Meeus and it is open-source on GitHub:
There's an old C library called Astrolog that can probably do some of the stuff you're asking. You can check it out here: http://www.astrolog.org/astrolog.htm
On top of Andrew Hammond answer, I just use Xcode to download the AA. I then remove all the Test files (AATest.cpp AATest.sin AATest.vcproj) and with a warning by Xcode of "Implicit conversion loss integer precision 'long' to 'int'" in the last line on nYear / 100
CAAEasterDetails CAAEaster::Calculate(long nYear, bool GregorianCalendar)
{
CAAEasterDetails details;
if (GregorianCalendar)
{
int a = nYear % 19;
int b = nYear / 100;
The program compile ok. Only compile if the program is objective c but not if it is Swift based. Got a problem with pre-processor macro AAPLUS_EXT_CLASS.
来源：https://stackoverflow.com/questions/2348415/objective-c-astronomy-library