Swift 2.0 String to NSDate - string

Question

Hello i get my date from Datepicker that gets saved to a string then uploaded to Firebase. The string is then recieved to the phone. The problem is that i want to convert this string to NSDate when i retrieve it.
This is how i get a string from datepicker
func datePickerChanged(datePicker:UIDatePicker){
var dateFormatter = NSDateFormatter()
dateFormatter.dateStyle = NSDateFormatterStyle.ShortStyle
dateFormatter.timeStyle = NSDateFormatterStyle.ShortStyle
var strDateFrom = dateFormatter.stringFromDate(datePicker.date)
fromDate = strDateFrom
print(fromDate)}
When i retrieve the date i get it as a string this is the print
print(self.membershipActiveTo)
And this is the print log
5/11/16, 2:35 PM
And below is the line of code i have tried to convert to string but it only returns nil
let strDate = self.membershipActiveTo // "2015-10-06T15:42:34Z"
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm"
print ( dateFormatter.dateFromString( strDate ) )

Answer 1

There are things to consider when working with dates and one of them is how to store the date in a consistent format that can be easily worked with for different uses. In your case, you may want to sort by date and if the data is stored like this
5/11/16, 2:35 PM
It's not going to be sortable. So, a different format is needed and here's one possible example
20160511143500
Here's some code to manipulate dates:
Write a nicely formatted date to Firebase
let d = NSDate()
//create a custom date string & save in firebase
let dateFormatterCustom = NSDateFormatter()
dateFormatterCustom.dateFormat = "yyyyMMddhhmmss"
let customDateString = dateFormatterCustom.stringFromDate(d)
print(customDateString) //prints "20160511023500" just for testing
let timesRef = self.myRootRef.childByAppendingPath("time_test")
let thisTimeRef = timesRef.childByAutoId()
let timeChildRef = thisTimeRef.childByAppendingPath("timestamp")
timeChildRef.setValue(customDateString)
Firebase now has this
time_test
-KFerAcANQv4pN1Pp4yW
timestamp: "20160418033309"
Then to read in from Firebase:
let timesRef = self.myRootRef.childByAppendingPath("time_test")
timesRef.observeEventType(.ChildAdded, withBlock: { snapshot in
let timeStamp = snapshot.value.objectForKey("timestamp") as! String
print(timeStamp) //still looks like 20160418033309
let shortDateString = self.timeStampToDateString(timeStamp)
print(shortDateString) //prints 4/18/16, 3:33 AM
})
and the function that converts the timestamp style string to a human readable one
func timeStampToDateString(stamp: String) -> String {
//create a custom date string & create a date object from it
let dateFormatterCustom = NSDateFormatter()
dateFormatterCustom.locale = NSLocale(localeIdentifier: "US_en")
dateFormatterCustom.dateFormat = "yyyyMMddhhmmss"
let d = dateFormatterCustom.dateFromString(stamp)!
//create a short date style string and format the string
let dateFormatterShortStyle = NSDateFormatter()
dateFormatterShortStyle.dateStyle = NSDateFormatterStyle.ShortStyle
dateFormatterShortStyle.timeStyle = NSDateFormatterStyle.ShortStyle
let dateString = dateFormatterShortStyle.stringFromDate(d)
return dateString
}
There's a lot of extra code in this example so it could be shortened considerably but I wanted to leave in all of the steps.