swift 3.0 Data to String?

Question

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {}

I want deviceToken to string

but:

let str = String.init(data: deviceToken, encoding: .utf8)

str is nil

swift 3.0

how can I let data to string ?

Registering for Push Notifications in Xcode 8/Swift 3.0? not working and the answer is a few months ago, I had tried it:

and print:

Next time you ask someone to try out your code make sure it's not pasted as image.. — Desdenova, Sep 21 '16 at 14:39
If someone comes across this when reading a file, check that the file is UTF8 encoded: `file -I /path/to/file.txt`. If not convert using iconv: `iconv -f UTF-16LE -t UTF-8 /path/to/file.txt > /path/to/utf8/file.txt` — Pulkit Goyal, Apr 10 '17 at 08:02

score 168 · Accepted Answer · answered Jan 10 '17 at 01:39

168

I came looking for the answer to the Swift 3 Data to String question and never got a good answer. After some fooling around I came up with this:

var testString = "This is a test string"
var somedata = testString.data(using: String.Encoding.utf8)
var backToString = String(data: somedata!, encoding: String.Encoding.utf8) as String!

answered Jan 10 '17 at 01:39

4redwings

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I had try you answer. It's worked in other func, but not working in `func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data)`.I do not know why? – weijia.wang Jan 10 '17 at 13:35
the device token is not a utf8 string, it is raw binary – Hogdotmac Jul 31 '17 at 10:04
so what to do if it is raw binary? – Kingalione Sep 13 '17 at 12:02
String.Encoding.utf8.rawValue -- for anyone in the latest Swift – Stephen J Mar 30 '18 at 17:38
1

for decoding token using didRegisterForRemoteNotificationsWithDeviceToken see this: https://stackoverflow.com/questions/37956482/registering-for-push-notifications-in-xcode-8-swift-3-0 – pw2 Nov 05 '18 at 15:32

luhuiya · Answer 2 · 2018-11-26T04:05:26.243

39

here is my data extension. add this and you can call data.ToString()

import Foundation

extension Data
{
    func toString() -> String?
    {
        return String(data: self, encoding: .utf8)
    }
}

edited Nov 26 '18 at 04:05

answered Dec 20 '17 at 05:59

luhuiya

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This is very bad coding - you should never force unwrap this since the encoding can always fail and this would crash the app. Instead return an optional string like the Apple API does for very good reasons. – Walter White Nov 21 '18 at 10:38
@WalterWhite yeah in the application i return optional string. but not update this answer, thanks for the comment – luhuiya Nov 26 '18 at 04:06
1

If you pass encoding as a parameter, maybe default it to .utf8 if you like, you can then use this for more than a single encoding type. – Micah Montoya May 06 '19 at 13:59

score 19 · Answer 3 · edited Jul 31 '17 at 10:04

19

let str = deviceToken.map { String(format: "%02hhx", $0) }.joined()

edited Jul 31 '17 at 10:04

Bugs

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answered Jul 31 '17 at 10:03

Hogdotmac

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score 7 · Answer 4 · edited Dec 25 '17 at 03:00

7

I found the way to do it. You need to convert Data to NSData:

let characterSet = CharacterSet(charactersIn: "<>")
let nsdataStr = NSData.init(data: deviceToken)
let deviceStr = nsdataStr.description.trimmingCharacters(in: characterSet).replacingOccurrences(of: " ", with: "")
print(deviceStr)

edited Dec 25 '17 at 03:00

Nookaraju

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answered Sep 22 '16 at 02:32

weijia.wang

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which characterSet is this ? – Kingalione Sep 13 '17 at 12:00
Let's avoid using NSData with Swift. – Brennan Apr 13 '18 at 05:16
Don't use this method. It's unsafe. – Bogdan Oct 21 '19 at 11:31

score 2 · Answer 5 · answered Nov 05 '17 at 03:55

This is much easier in Swift 3 and later using reduce:

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    let token = deviceToken.reduce("") { $0 + String(format: "%02x", $1) }

    DispatchQueue.global(qos: .background).async { 
        let url = URL(string: "https://example.com/myApp/apns.php")!

        var request = URLRequest(url: url)
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        request.httpMethod = "POST"
        request.httpBody = try! JSONSerialization.data(withJSONObject: [
            "token" : token, 
            "ios" : UIDevice.current.systemVersion,
            "languages" : Locale.preferredLanguages.joined(separator: ", ")
            ])

        URLSession.shared.dataTask(with: request).resume()
    }
}

score 2 · Answer 6 · answered Sep 27 '18 at 09:57

2

Swift 4 version of 4redwings's answer:

let testString = "This is a test string"
let somedata = testString.data(using: String.Encoding.utf8)
let backToString = String(data: somedata!, encoding: String.Encoding.utf8)

answered Sep 27 '18 at 09:57

Abhishek Jain

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score 1 · Answer 7 · answered Jan 06 '20 at 14:09

1

You can also use let data = String(decoding: myStr, as: UTF8.self) here is a resource about converting data to string

answered Jan 06 '20 at 14:09

atalayasa

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score 1 · Answer 8 · answered May 18 '20 at 07:47

for swift 5

let testString = "This is a test string"
let somedata = testString.data(using: String.Encoding.utf8)
let backToString = String(data: somedata!, encoding: String.Encoding.utf8) as String?
print("testString > \(testString)")
//testString > This is a test string
print("somedata > \(String(describing: somedata))")
//somedata > Optional(21 bytes)
print("backToString > \(String(describing: backToString))")
//backToString > Optional("This is a test string")

score 0 · Answer 9 · answered Oct 31 '17 at 21:17

To extend on the answer of weijia.wang:

extension Data {
    func hexString() -> String {
        let nsdataStr = NSData.init(data: self)
        return nsdataStr.description.trimmingCharacters(in: CharacterSet(charactersIn: "<>")).replacingOccurrences(of: " ", with: "")
    }
}

use it with deviceToken.hexString()

score 0 · Answer 10 · edited Jun 20 '20 at 09:12

According to the Apple doc below, device token can not be decoded. So, I think the best thing to do is just leave it be.

https://developer.apple.com/library/content/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/APNSOverview.html

Security Architecture

A device token is an opaque NSData instance that contains a unique identifier assigned by Apple to a specific app on a specific device. Only APNs can decode and read the contents of a device token. Each app instance receives its unique device token when it registers with APNs, and must then forward the token to its provider, as described in Configuring Remote Notification Support. The provider must include the device token in each push notification request that targets the associated device; APNs uses the device token to ensure the notification is delivered only to the unique app-device combination for which it is intended.

score 0 · Answer 11 · edited Oct 19 '18 at 07:36

0

If your data is base64 encoded.

if ( dataObj != nil ) {
    let encryptedDataText = dataObj!.base64EncodedString(options: NSData.Base64EncodingOptions())
    NSLog("Encrypted with pubkey: %@", encryptedDataText)
}

edited Oct 19 '18 at 07:36

Suraj Rao

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answered Oct 19 '18 at 07:23

jeet.chanchawat

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score 0 · Answer 12 · edited Jan 18 '20 at 22:30

let urlString = baseURL + currency

    if let url = URL(string: urlString){
        let session = URLSession(configuration: .default)        
        let task = session.dataTask(with: url){ (data, reponse, error) in
            if error != nil{
                print(error)
                return
            }


            let dataString = String(data: data!, encoding: .utf8)
            print(dataString)

        }

        task.resume()

    }

swift 3.0 Data to String?

12 Answers12