迅速在格林尼治标准时间获取两个日期之间的差额

Question

I recently noticed strange behaviour trying to find the difference between two dates (in seconds).

I have a datestring that is in GMT time:

2016-01-07 01:09:47.289000

I want to find how many seconds since that time NOW.

But I notice that when I use NSDate() I get the time of my local time, not GMT time.

How would I go about doing this?

Answer 1

Use the NStimeZone class to set time zone

let date = NSDate()
var formatter = NSDateFormatter()
let gmt = NSTimeZone(abbreviation: "GMT")
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss ZZZ"
formatter.timeZone = gmt
formatter.stringFromDate(date)

To compare, convert the current date from NSDate to "GMT" and then calculate the time interval between the two.