How do I format JSON Date String with Swift?

Question

I make an http get request to a server and get back a json object with a date string like this:

{
    name = "Place1";
    temperature = 79;
    humidity = 68;
    reported_at = "2013-07-21T19:32:00Z";
}

I want to format the reported_at key so I can display a readable date and time to the user.

This is the swift code I am trying which keeps returning nil, as it cannot format the date.

    var str = "2013-07-21T19:32:00Z"

    var dateFor: NSDateFormatter = NSDateFormatter()
    dateFor.dateFormat = "yyyy-MM-dd'T'HH:mm:ss:SSS"

    var yourDate: NSDate? = dateFor.dateFromString(str)

    println(yourDate)

How can I format this date and time with Swift correctly? I want to display the date and time to the user so they can know when the reading was taken.

vadian · Accepted Answer · 2019-02-01 15:56:12Z

33

Nowadays (September 2017) in Swift 4 there are smarter ways to decode ISO8601:

ISO8601DateFormatter

let str = "2013-07-21T19:32:00Z"
let formatter = ISO8601DateFormatter()
let yourDate = formatter.date(from: str)

JSONDecoder

struct Place : Decodable {

    let name : String
    let temperature : Int
    let humidity : Int
    let reportedAt : Date

}

let json = """
{"name" : "Place1", "temperature" : 79, "humidity" : 68, "reported_at" : "2013-07-21T19:32:00Z"}
"""
let data = Data(json.utf8)

let decoder =  JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
decoder.keyDecodingStrategy = .convertFromSnakeCase
let place = try! decoder.decode(Place.self, from: data)

edited Feb 1, 2019 at 15:56

answered Sep 30, 2017 at 7:17

vadian

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1 Comment

Rob C Over a year ago

Available in ios 10 and up

Community · Accepted Answer · 2018-01-17 06:06:05Z

28

Use the following string format to convert a server string into a Date

dateFor.dateFormat = "yyyy-MM-dd'T'HH:mm:ss"

edited Jan 17, 2018 at 6:06

CommunityBot

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answered Feb 26, 2015 at 16:59

Zell B.

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8 Comments

rmaddy Over a year ago

DO NOT quote the Z. That will give the wrong result.

Zell B. Over a year ago

@rmaddy just tried it and not quoting 'Z' is giving me a wrong

rmaddy Over a year ago

@zellb I can assure you that quoting the Z will give the wrong result. If you think you get the wrong result when you don't quote the Z then you are doing something else incorrectly or misunderstanding the result.

rmaddy Over a year ago

The date 2015-02-27T11:24:00Z is at 11:24am in GMT time (that's what the Z means in the date string). You must live in the GMT+1 timezone. Correct? If you don't quote the Z, the date string is properly interpreted in GMT time. If you do quote the Z, the date string is incorrectly interpreted in local time.

Leo Dabus Over a year ago

"yyyy-MM-dd'T'HH:mm:ssX" should be the correct date format

|

LightMan · Accepted Answer · 2017-09-11 10:47:20Z

4

If you are using SwiftDate (you probably should!) simply use:

Serialize:

let date:NSDate = ....
let dateInRegion = DateInRegion( absoluteTime: date )
let serializedString:String = dateInRegin.toString( .ISO8601Format( .Full ))!

Deserialize:

let serializedDate:String = "2016-03-01T22:10:55.200Z"
let date:NSDate? = serializedDate.toDateFromISO8601()

edited Sep 11, 2017 at 10:47

LightMan

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answered Mar 1, 2016 at 20:19

Marchy

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1 Comment

Albert Tong Over a year ago

SwiftDate can be found at this link: github.com/malcommac/SwiftDate

Changnam Hong · Accepted Answer · 2017-09-30 06:47:51Z

1

Here is my answer using extension in Swift4.

extension String {
  func toDate(dateFormat: String) -> Date? {

    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = dateFormat

    let date: Date? = dateFormatter.date(from: self)
    return date
}

Simple Usage

let str = "2013-07-21T19:32:00Z";
let dateStr = str.toDate(dateFormat: "yyyy-MM-dd'T'HH:mm:ssZ")

Also, Check dateFormat that you want from here. ISO 8601

answered Sep 30, 2017 at 6:47

Changnam Hong

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3 Comments

vadian Over a year ago

In Swift 4 I'd prefer ISO8601DateFormatter or decode the JSON directly with JSONDecoder

Changnam Hong Over a year ago

@vad Yes, Using JSONDecoder will be better. But, ISO8601DateFormatter, it does not support milliseconds. stackoverflow.com/questions/41847672/…

vadian Over a year ago

There are no milliseconds in the question and in macOS 10.13 / iOS 11 milliseconds are supported.

Dilip Tiwari · Accepted Answer · 2017-09-23 05:51:37Z

0

For Converting JSON String to Date & Time in Swift 3.0 Use Below Code:-

    let timeinterval : TimeInterval = (checkInTime as! NSString).doubleValue
    let dateFromServer = NSDate(timeIntervalSince1970:timeinterval)
    print(dateFromServer)
    let dateFormater : DateFormatter = DateFormatter()
    //dateFormater.dateFormat = "dd-MMM-yyyy HH:mm a"  // 22-Sep-2017 14:53 PM
    dateFormater.dateFormat = "dd-MMM-yyyy hh:mm a"   // 22-Sep-2017 02:53 PM
    print(dateFormater.string(from: dateFromServer as Date))

where checkInTimewill be your String.Hope it will help someone

answered Sep 23, 2017 at 5:51

Dilip Tiwari

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Comments

Pietro Messineo · Accepted Answer · 2021-05-03 07:06:13Z

In Swift 5 you can do something like this (This is a variation of vadian's answer) in case you have a custom date string that is not in 'iso8601':

struct Place : Decodable {

    let name : String
    let temperature : Int
    let humidity : Int
    let reportedAt : Date

}

let json = """
{"name" : "Place1", "temperature" : 79, "humidity" : 68, "reported_at" : "2021-05-02 06:00"}
"""
let data = Data(json.utf8)

//FORMAT DATE
let dateFormatter = DateFormatter()
//Force dateFormatter to be always 24h
dateFormatter.setLocalizedDateFormatFromTemplate("HH:mm a")
dateFormatter.amSymbol = ""
dateFormatter.pmSymbol = ""
dateFormatter.locale = Locale(identifier: "en_US")
dateFormatter.dateFormat = "yyyy-MM-dd HH:mm"

let decoder =  JSONDecoder()
decoder.dateDecodingStrategy = .formatted(dateFormatter)
decoder.keyDecodingStrategy = .convertFromSnakeCase
let place = try! decoder.decode(Place.self, from: data)

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