迅速3.0数据到字符串？

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

我想deviceToken串

但：

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

str 是 nil

迅捷3.0

我怎么才能让data来string？

在Xcode 8 / Swift 3.0中注册推送通知？ 无法正常工作，答案是在几个月前，我已经尝试过了：

并打印：

我来寻找Swift 3数据到字符串问题的答案，但从来没有一个好的答案。经过一番鬼混之后，我想到了这个：

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!

这是我的数据扩展名。添加它，您可以调用data.ToString（）

import Foundation

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

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

我找到了方法。您需要转换Data为NSData：

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

在Swift 3和以后使用reduce的情况下，这要容易得多：

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()
    }
}

Swift 4版本的4redwings的答案：

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

您还可以let data = String(decoding: myStr, as: UTF8.self)在这里使用有关将数据转换为字符串的资源

扩展weijia.wang的答案：

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

与它一起使用 deviceToken.hexString()

如果您的数据是base64编码的。

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

根据下面的Apple文档，无法对设备令牌进行解码。因此，我认为最好的办法就是保持现状。

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

安全架构

设备令牌是不透明的NSData实例，其中包含Apple分配给特定设备上特定应用程序的唯一标识符。只有APN才能解码和读取设备令牌的内容。每个应用程序实例在向APN注册时都会收到其唯一的设备令牌，然后必须将令牌转发到其提供程序，如配置远程通知支持中所述。提供者必须在针对关联设备的每个推送通知请求中包含设备令牌；APN使用设备令牌来确保仅将通知传递给预期的唯一应用程序设备组合。

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()

    }

快速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")