NSDate being interpreted several hours off (minutes and day working fine) - ios

Question

I am updating the question to be more precise, thank you for the feedback already.
So I am setting a cell for a tableview and displaying the time of the event on the cell itself and to do so am using Parse. The date is downloading correctly from parse as evidenced by the first println, but when I make the label text equal the dateToString of the when date (which is the one from parse) it throws it off by several hours for some reason. The simulator however displays the right time on the status bar and the phones gps is set to EST as well... So I am very confused.
Here is the entire function:
func configureCell(object : PFObject)-> Void {
eventNameText.text = (object.objectForKey("name") as? String)!
var when = (object.objectForKey("when") as? NSDate)!
numEchoesText.text = String(stringInterpolationSegment: object.objectForKey("numEchoes")!)
println(when)
var formatter = NSDateFormatter()
formatter.dateFormat = "EEEE, h:mm a"
parseid = object.objectId!
if (contains(echoes, parseid)) {
echoImage.setImage(imageEchoed, forState: .Normal)
}
else {
echoImage.setImage(imageUnechoed, forState: .Normal)
}
var now = NSDate()
whenText.text = formatter.stringFromDate(when)
println(formatter.stringFromDate(now))
println(formatter.stringFromDate(when))
self.object = object
}
And here is the result:
2015-05-31 23:43:00 +0000
Tuesday, 9:30 AM
Sunday, 7:43 PM
Please note that the first time is correct but the datetostring is interpreting it as the third line. I added a middle println to display the current date in order to show that the datetostring is working correctly for the now date.
Thanks in advance for any help!!

Answer 1

Edit: updated answer based on new details.
Your trouble is because of the timezone. NSDate does not store any time zone information.
println(when)
--> 2015-05-31 23:43:00 +0000 // notice the timezone is 0000 / GMT
Adding a timezone to the NSDateFormatter will help you see what's going on behind the scene:
var formatter = NSDateFormatter()
formatter.dateFormat = "EEEE, h:mm a z"
println(formatter.stringFromDate(when))
--> Sunday, 7:43 PM xyz // Depends on the timezone on your device
The two represents the same point in time, but expressed in different timezones. To solve this, you need to set the timezone of the formatter to GMT:
var formatter = NSDateFormatter()
formatter.dateFormat = "EEEE, h:mm a z"
formatter.timeZone = NSTimeZone.init(name:"GMT")
println(formatter.stringFromDate(when))
--> Sunday, 11:43 PM GMT
You can remove the timezone identifier now that you get it correct. Date & time manipulation in Cocoa / iOS are a lot more complicated than other languages (Java, C#, Javascript, etc.) Sometimes I wish Apple just created a NSDate class with methods to add & subtract date/time components, switch timezone, etc. I can dream on.

Answer 2

Take a look at NSDateFormatter and how it works. If I do understand your question clearly, I think this should work.
var dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd hh:mm"
dateFormatter.stringFromDate(parseDateObject)

Answer 3

2015-05-31 23:43:00 +0000 means "the 31st of May 2015 at 23:43:00 at +0000 from UTC".
According to your question "The simulator however displays the right time on the status bar and the phones gps is set to EST".
If you convert that date from UTC to EST you get "Sunday, 7:43 PM".
Your NSDate is therefore being interpreted perfectly.
Making reasonable assumptions about the Parse API, it looks like somebody has imported your data incorrectly.