swift 3.0 Data to String?

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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)

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最佳答案

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!

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

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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()

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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()
}
}

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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.

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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)
}
}

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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)

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If your data is base64 encoded.

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

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

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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()


}

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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")