Swift convert to date from string in Parse user object

Question

This is not working for me. I have a value I'm getting from a database that's clearly a valid Date and I can print it out fine:

let datefromu = "\(PFUser.current()!.object(forKey:"original_date_route_started")!)"
print("I fetched \(datefromu)")

that prints: I fetched 2017-08-10 15:50:43 +0000.

I must add that if I look in the raw database it is written as so: 2017-08-10T15:50:43.436Z

so I think that output is already Parse's way of formatting the output from the date field?

Bottom line, when I want to populate a date variable I have (original_date_route_started: Date?) and convert that string to a date, I'm getting nil!:

let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
self.original_date_route_started = formatter.date(from: datefromu)

It seems that datefromu is already a Date and not a String. — rmaddy
– rmaddy, Commented Aug 10, 2017 at 16:50
Are you sure you didn't want to write formatter.string(from: datefromu)? — David Pasztor
– David Pasztor, Commented Aug 10, 2017 at 16:54
@rmaddy you are right. But how can I set it to my date variable? Swift doesn't know its a date. — Chaim Friedman
– Chaim Friedman, Commented Aug 10, 2017 at 16:56
@DávidPásztor no. I need a date not a string. And I already tried converting to string and back today again but to no avail. same issue — Chaim Friedman
– Chaim Friedman, Commented Aug 10, 2017 at 16:58
Use subclassing to avoid manual conversion of data types in Parse. If you have already set original_date_route_started's type as a Date in the Schema (using the dashboard or the REST API), it will be converted to Date (swift) / NSDate (objc). — nathan
– nathan, Commented Aug 10, 2017 at 17:01

nathan · Accepted Answer · 2017-08-10 18:19:05Z

1

Do you want to convert PFUser.current()!.object(forKey:"original_date_route_started") to a Date ? Then you should consider subclassing to avoid dealing with DateFormatters:

Assuming original_date_route_started is correctly defined as a Date in Parse (if not, I'll update the answer):

import Foundation
import Parse

class UserParse: PFUser {

    @NSManaged var original_date_route_started: Date?

}

If you want to set a new value to it:

var user = UserParse.current()!
user.original_date_route_started = Date(timeIntervalSinceNow: -3600 * 4) // 4hs ago
user.saveInBackground()

// Your sample code:
let datefromu = UserParse.current()!.original_date_route_started
self.original_date_route_started = datefromu

Are you just having problems setting self.original_date_route_started's value in another class that's not PFUser ? There are 2 ways to do it:

ISO8601DateFormatter for iOS >= 10 (See source code for more details)
```
let isoDateFormatter= ISO8601DateFormatter()
```

Custom DateFormatter for iOS >= 2

var isoDateFormatter: DateFormatter = {
    $0.locale     = Locale(identifier:"en_US_POSIX")
    $0.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
    $0.timeZone   = TimeZone(secondsFromGMT: 0) // Or Locale(identifier: "GMT")
    return $0
}(DateFormatter())

Converting string to date:

let testString = "2017-08-10T17:53:51+0000"
isoDateFormatter.date(from: testString)

edited Aug 10, 2017 at 18:19

answered Aug 10, 2017 at 17:30

nathan

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4 Comments

Chaim Friedman Over a year ago

I'm using original_date_route_started as a date value in many areas in my class, not necessarily within the scope of the Parse user. So I have it way up on top and keep referring to it as self.original_date_route_started It is only when I don't have value for it , then I retrieve it from the Parse User in db, and am currently unsuccessfully trying to set it from that value

Chaim Friedman Over a year ago

yes and in your example, can you then set a variable that should be of type Date as so: self.original_date_route_started = isoDateFormatter.date(from: testString) I don't think so! - this is all I'm trying to do!

nathan Over a year ago

What do you mean with I don't think so! ? That's the API: func date(from string: String) -> Date?. Your DateFormatter was set up incorrectly, please use the code above (you forgot to setup the Locale / TZ and the format string is incorrect). Working example: swift.sandbox.bluemix.net/#/repl/598ca26ade80147f1a9d22f0

Chaim Friedman Over a year ago

Thanks for the sample. let me check that out

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