I have an app that relies heavily on date calculations. I am using NSCalendar and doing all the calculations "the right way", but I don't really have any way to test any other calendar besides the default US one.
How can you change the calendar used on iOS? Where can I find more information about calendar alternatives?
You can simply change it on your Device/Simulator. Open Settings -> General -> International. Here you can change the format of the calendar date or the calendar itself.