This is my code :
println(myStringDate) // 2015-02-26T17:46:34.000Z
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = \"YYYY-MM-DDTHH:mm:ss
Your problem is how you set the date format. Because there is a T in your string, you need to "escape" it and say, that it shouldn't affect the formatting of the date.
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
Also as you see, I've changed the sss to SSS which stands for miliseconds and also changed the year YYYY to lowercase yyyy also the same with the DD. You have to be really carefully, when to use upper and lowercase letters in your Dateformat-strings.
Check @HotLicks link in the comments which shows a great overview of the dateformat usage.
I know that it's to late, but
dateFormatter.dateFormat = "YYYY-MM-DD'T'HH:mm:ss.sss'Z'"
should be
dateFormatter.dateFormat = "YYYY-MM-DD'T'HH:mm:ss.SSS'Z'"
because,
1)
ss - seconds
SSS - fractional second
sss != SSS
2)
T -> 'T'; S -> 'S'
And nice tutorial