Creating NSData from NSString in Swift

Question

I'm trying to ultimately have an NSMutableURLRequest with a valid HTTPBody, but I can't seem to get my string data (coming from a UITextField) into a usable NSData object.

I've seen this method for going the other way:

NSString(data data: NSData!, encoding encoding: UInt)

But I can't seem to find any documentation for my use case. I'm open to putting the string into some other type if necessary, but none of the initialization options for NSData using Swift seem to be what I'm looking for.

Gabriele Petronella · Accepted Answer · 2016-08-22 09:37:29Z

373

In Swift 3

let data = string.data(using: .utf8)

In Swift 2 (or if you already have a NSString instance)

let data = string.dataUsingEncoding(NSUTF8StringEncoding)

In Swift 1 (or if you have a swift String):

let data = (string as NSString).dataUsingEncoding(NSUTF8StringEncoding)

Also note that data is an Optional<NSData> (since the conversion might fail), so you'll need to unwrap it before using it, for instance:

if let d = data {
    println(d)
}

edited Aug 22, 2016 at 9:37

answered Jun 4, 2014 at 14:16

Gabriele Petronella

108k21 gold badges223 silver badges238 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

Nicolas Manzini Over a year ago

Swift can infer NSData type?

Gabriele Petronella Over a year ago

@NicolasManzini sure it can, as with any other type.

Gabriele Petronella Over a year ago

@macdonjo yep, that API changed over time and now it returns an Optional<NSData>, which you need to unwrap before using

LiangWang Over a year ago

In Swift2, there's no need to use "as" cast since it's automatically bridged

Martin R Over a year ago

A conversion to UTF-8 cannot fail, therefore an optional binding it not really needed, you can force-unwrap here.

|

Said Sikira · Accepted Answer · 2017-06-07 12:13:51Z

34

Swift 4 & 3

Creating Data object from String object has been changed in Swift 3. Correct version now is:

let data = "any string".data(using: .utf8)

edited Jun 7, 2017 at 12:13

answered Aug 19, 2016 at 13:12

Said Sikira

4,54331 silver badges43 bronze badges

2 Comments

raddevus Over a year ago

Thanks. This worked for me in swift 3 perfectly. let input = "test string" let xdata = input.data(using: String.Encoding.utf8)

Happiehappie Over a year ago

Any idea why String(data: data!, encoding: .nonLossyASCII) will be nil?

oguz ismail · Accepted Answer · 2019-05-01 19:05:23Z

6

In swift 5

let data = Data(YourString.utf8)

edited May 1, 2019 at 19:05

oguz ismail

51.8k16 gold badges64 silver badges83 bronze badges

answered May 1, 2019 at 18:43

Sanjay Mishra

7028 silver badges19 bronze badges

Comments

Sumit · Accepted Answer · 2020-04-01 14:32:03Z

5

Convert String to Data

extension String {
    func toData() -> Data {
        return Data(self.utf8)
    }
}

Convert Data to String

extension Data {
      func toString() -> String {
          return String(decoding: self, as: UTF8.self)
      }
   }

answered Apr 1, 2020 at 14:32

Sumit

95410 silver badges10 bronze badges

Comments

Shafraz Buhary · Accepted Answer · 2014-10-30 08:42:43Z

4

Here very simple method

let data = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false)

answered Oct 30, 2014 at 8:42

Shafraz Buhary

6656 silver badges15 bronze badges

Comments

TheTiger · Accepted Answer · 2018-05-18 12:53:30Z

4

Swift 4

let data = myStringVariable.data(using: String.Encoding.utf8.rawValue)

edited May 18, 2018 at 12:53

TheTiger

13.4k4 gold badges60 silver badges84 bronze badges

answered Mar 6, 2018 at 4:41

jatin

1797 bronze badges

1 Comment

vadian Over a year ago

Don't use NSString in Swift.

Vinod Joshi · Accepted Answer · 2014-11-05 06:42:23Z

3

// Checking the format
var urlString: NSString = NSString(data: jsonData, encoding: NSUTF8StringEncoding)

// Convert your data and set your request's HTTPBody property
var stringData: NSString = NSString(string: "jsonRequest=\(urlString)")

var requestBodyData: NSData = stringData.dataUsingEncoding(NSUTF8StringEncoding)!

answered Nov 5, 2014 at 6:42

Vinod Joshi

7,8781 gold badge52 silver badges51 bronze badges

Comments

Ramis · Accepted Answer · 2018-11-21 07:24:53Z

3

To create not optional data I recommend using it:

let key = "1234567"
let keyData = Data(key.utf8)

answered Nov 21, 2018 at 7:24

Ramis

17.1k8 gold badges93 silver badges113 bronze badges

1 Comment

vadian Over a year ago

In Swift 3+ this is the most efficient way.

meMadhav · Accepted Answer · 2019-01-09 14:28:03Z

3

Swift 4.2

let data = yourString.data(using: .utf8, allowLossyConversion: true)

answered Jan 9, 2019 at 14:28

meMadhav

2653 silver badges14 bronze badges

Collectives™ on Stack Overflow

Creating NSData from NSString in Swift

9 Answers 9

8 Comments

Swift 4 & 3

2 Comments

Comments

Comments

Comments

1 Comment

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

9 Answers 9

8 Comments

Swift 4 & 3

2 Comments

Comments

Comments

Comments

1 Comment

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related