Swift 问题中的 NSData 到字符串

Question

我在 swift 中将我的 NSData 转换为 NSString 时遇到问题。我正在使用我认为正确的命令和格式：NSString(data: <DATA>, encoding: <ENCODING>) 但是无论我做什么，我都会以 nil 值结束。我正在运行最新的 Xcode 测试版，所以我不确定这是否相关，但我希望它是我运行遇到的一个简单的错误。

我附上了 playground 代码和屏幕截图。

Xcode 6.3 Beta 2 版本 (6D532l)

的游乐场代码

import Foundation

//: # NSData to String Conversion Playground
//: ### Step 1
//: The first step is to take an array of bytes and conver them into a NSData object.  The bytes are as follows:

var testBytes : [UInt8] = [0x14, 0x00, 0xAB, 0x45, 0x49, 0x1F, 0xEF, 0x15, 0xA8, 0x89, 0x78, 0x0F, 0x09, 0xA9, 0x07, 0xB0, 0x01, 0x20, 0x01, 0x4E, 0x38, 0x32, 0x35, 0x56, 0x20, 0x20, 0x20, 0x00]

//: ### Step 2
//: Convert the byte array into an **NSData** Object

var immutableData = NSData(bytes: testBytes, length: testBytes.count)

//: ### Step 3
//: Attempt to convert the **NSData** object into a string so it can be sent around as ascii.  This for some reason seems to be failing, however.

var convertedString = NSString(data: immutableData, encoding: NSUTF8StringEncoding)

println("String = \(convertedString)")

Playgound 的结果

Answer 1

使用有效的 UTF8 字符！

// Playground - noun: a place where people can play
import UIKit
var str = "Hello, playground"
import Foundation
//: # NSData to String Conversion Playground
//: ### Step 1
//: The first step is to take an array of bytes and conver them into a NSData object.  The bytes are as follows:

// Hello World
var testBytes : [UInt8] = [0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x20, 0x57, 0x6F, 0x72, 0x6C, 0x64]

//: ### Step 2
//: Convert the byte array into an **NSData** Object

var immutableData = NSData(bytes: testBytes, length: testBytes.count)

//: ### Step 3
//: Attempt to convert the **NSData** object into a string so it can be sent around as ascii.  This for some reason seems to be failing, however.

var convertedString = NSString(data: immutableData, encoding: NSUTF8StringEncoding)

println("String = \(convertedString)")

您的输出将是： "String = Optional(Hello World)"

Answer 2

let testBytes : [UInt8] = [0x48, 0x65, 0x6C, 0x6C, 0x6F, 0x20, 0x57, 0x6F, 0x72, 0x6C, 0x64]


func bytes2String(array:[UInt8]) -> String {
    return String(data: NSData(bytes: array, length: array.count), encoding: NSUTF8StringEncoding) ?? ""
}

Xcode 8.2 • Swift 3.0.2

func bytes2String(_ array: [UInt8]) -> String {
    return String(data: Data(bytes: array, count: array.count), encoding: .utf8) ?? ""
}

测试：

bytes2String(testBytes)  // "Hello World"

Answer 3

如果您只想要字符串中的十六进制值：

I just want a string of the hex values. I guess this is trying to decode as actual ascii! Duh!! – Jeef Mar 4 at 23:29

最简单的方法就是使用内置字符串插值的 Swifts。

 let myHexString = "\(myNSDataObject)"

这将为您提供一个十六进制字符串，每两个字符之间有空格，并用方括号括起来。像这样：

 <a0 ff 21 4a>

您可以使用内置的字符串方法对其进行格式化：

 myHexString.stringByTrimmingCharactersInSet(NSCharacterSet(charactersInString: "<>")).stringByReplacingOccurrencesOfString(" ", withString: "")

您将得到一个包含以下内容的字符串：a0ff214a

Answer 4

在 Swift 3.0

中使用 UTF8

 let testBytes : [UInt8] = [0x14, 0x00, 0xAB, 0x45, 0x49, 0x1F, 0xEF, 0x15, 0xA8, 0x89, 0x78, 0x0F, 0x09, 0xA9, 0x07, 0xB0, 0x01, 0x20, 0x01, 0x4E, 0x38, 0x32, 0x35, 0x56, 0x20, 0x20, 0x20, 0x00]

 let immutableData = NSData(bytes: testBytes, length: testBytes.count)

 let convertedString = NSString(data: (immutableData as NSData) as Data, encoding:String.Encoding.utf8.rawValue)

 print("String = \(convertedString)")

Swift 问题中的 NSData 到字符串

NSData to String in Swift Issues

ios

xcode

swift

nsdata

Xcode 6.3 Beta 2 版本 (6D532l)

Playgound 的结果