NSTimeZone list contiains duplicate time zones?

Question

When listing all time zones returned by [NSTimeZone knownTimeZoneNames] on an iPhone 4, there are some that appear to be functional duplicates. They're listed largely by city. For example, I would expect America/Chicago and America/Indiana/Knox to both equate to the Central Time Zone (see here for a time zone reference). Am I missing a difference between them? Or is it just Apple being user-friendly by letting the user choose their zone by city?

Answer 1

Indiana is odd when it comes to time zones.

Keep in mind that if a particular area was ever different from the areas around it, it needs a new time zone defined, because you could ask for a time at any point in history.

Different areas of Indiana have moved to different time zones in the past to coincide with major metropolis areas close to them (Louisville and Chicago in particular), and some of them even started or stopped observing daylight savings time which made them "in sync" with places near them only part of the year.

All of this means more time zones in ios in order to cover all of the different scenarios, both now, and in the past.