[swift] swift 3.0 Data to String?

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:

enter image description here

and print:

enter image description here

This question is related to swift string

The answer is


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!

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)
    }
}

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

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)

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)

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()
    }
}

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


If your data is base64 encoded.

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

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()

    }

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")

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.


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()


Questions with swift tag:

Make a VStack fill the width of the screen in SwiftUI Xcode 10.2.1 Command PhaseScriptExecution failed with a nonzero exit code Command CompileSwift failed with a nonzero exit code in Xcode 10 Convert Json string to Json object in Swift 4 iOS Swift - Get the Current Local Time and Date Timestamp Xcode 9 Swift Language Version (SWIFT_VERSION) How do I use Safe Area Layout programmatically? How can I use String substring in Swift 4? 'substring(to:)' is deprecated: Please use String slicing subscript with a 'partial range from' operator Safe Area of Xcode 9 The use of Swift 3 @objc inference in Swift 4 mode is deprecated? Swift error : signal SIGABRT how to solve it How to update the constant height constraint of a UIView programmatically? Convert NSDate to String in iOS Swift Waiting until the task finishes Type of expression is ambiguous without more context Swift Removing object from array in Swift 3 Date to milliseconds and back to date in Swift How does String substring work in Swift How does String.Index work in Swift Request Permission for Camera and Library in iOS 10 - Info.plist How to use addTarget method in swift 3 swift 3.0 Data to String? how to open an URL in Swift3 Get current date in Swift 3? Updating to latest version of CocoaPods? Swift programmatically navigate to another view controller/scene Correctly Parsing JSON in Swift 3 What is the 'open' keyword in Swift? Swift - How to detect orientation changes How to set Status Bar Style in Swift 3 how to make UITextView height dynamic according to text length? How to program a delay in Swift 3 How to set UICollectionViewCell Width and Height programmatically How can I mimic the bottom sheet from the Maps app? How do I write dispatch_after GCD in Swift 3, 4, and 5? How do I dispatch_sync, dispatch_async, dispatch_after, etc in Swift 3, Swift 4, and beyond? Default optional parameter in Swift function Swift: Display HTML data in a label or textView How to capture multiple repeated groups? How to pass data using NotificationCenter in swift 3.0 and NSNotificationCenter in swift 2.0? Convert string to date in Swift How to fix Error: this class is not key value coding-compliant for the key tableView.' Basic example for sharing text or image with UIActivityViewController in Swift Date Format in Swift How to display .svg image using swift How do I make a new line in swift 'Linker command failed with exit code 1' when using Google Analytics via CocoaPods Swift Error: Editor placeholder in source file Round up double to 2 decimal places How to make a UILabel clickable?

Questions with string tag:

How to split a string in two and store it in a field String method cannot be found in a main class method Kotlin - How to correctly concatenate a String Replacing a character from a certain index Remove quotes from String in Python Detect whether a Python string is a number or a letter How does String substring work in Swift How does String.Index work in Swift swift 3.0 Data to String? How to parse JSON string in Typescript How to change the datetime format in pandas How to write to a CSV line by line? convert string to number node.js "error: assignment to expression with array type error" when I assign a struct field (C) Remove 'b' character do in front of a string literal in Python 3 Ruby: How to convert a string to boolean What does ${} (dollar sign and curly braces) mean in a string in Javascript? How do I make a new line in swift converting json to string in python PHP - remove all non-numeric characters from a string C# - How to convert string to char? How can I remove the last character of a string in python? Converting std::__cxx11::string to std::string How to convert string to date to string in Swift iOS? Convert time.Time to string TypeError: a bytes-like object is required, not 'str' when writing to a file in Python3 How can I capitalize the first letter of each word in a string using JavaScript? Best way to verify string is empty or null Hive cast string to date dd-MM-yyyy Check for special characters in string How to convert any Object to String? Print "\n" or newline characters as part of the output on terminal Set the maximum character length of a UITextField in Swift How do I convert a Python 3 byte-string variable into a regular string? What does $ mean before a string? Delete the last two characters of the String Splitting a string into separate variables Figure out size of UILabel based on String in Swift Matching strings with wildcard How do I concatenate strings? Print very long string completely in pandas dataframe Check string for nil & empty Convert float to string with precision & number of decimal digits specified? How do I print my Java object without getting "SomeType@2f92e0f4"? enum to string in modern C++11 / C++14 / C++17 and future C++20 How should I remove all the leading spaces from a string? - swift Convert array to JSON string in swift Swift extract regex matches Convert a file path to Uri in Android How would I get everything before a : in a string Python