I was relieved to read the final paragraph. I have found NSDate/NSCalendar to be the best designed API for date and time calculations, and I never knew it was

I was relieved to read the final paragraph. I have found NSDate/NSCalendar to be the best designed API for date and time calculations, and I never knew it was built on top of ICU. It discourages bad assumptions while many others try to make a more 'fluent' interface that encourages them. When I first tried Joda in Java it had a builder interface that stank, I was able to easily write tests that produced the wrong date or threw an exception simply by changing the order of construction. But I think that's long gone.