swift中utc时区和设备时区之间的区别

Question

我正在开发一款聊天应用。我想确定UTC时区和设备当前时区之间的时差。如何在swift3中做到这一点？

Answer 1

 // Returns a Date initialized to the current date and time
 let currentDate = Date()

 // Returns the time zone currently used by the system
 let timeZone = NSTimeZone.system

 // Returns the difference in seconds between the receiver and Greenwich Mean Time at a given date.
 let timeZoneOffset = timeZone.secondsFromGMT(for: currentDate) / 3600

 print(timeZoneOffset, "hours offset for timezone", timeZone)

 // example output for Denver (considers daylight saving time)
 // -6  hours offset for timezone  America/Denver (current)