如何在iOS上的Swift中使用Big5编码 [英] How to use Big5 encoding in Swift on iOS

问题描述

我正在扫描一个用Big5编码的汉字的QR码. (大师概况)

I'm scanning a QR-Code with chinese characters encoded in Big5. (主页概况)

是否有机会在Swift 3中正确解码此String?

Is there a chance to get this String decoded correctly in Swift 3?

我在GitHub上找到了这个 Objective-C示例和这个

I found this Objective-C example on GitHub and this SO question, but there are no kCFStringEncodingBig5_HKSCS_1999 and kCFStringEncodingBig constants in Swift.

更新:

我找到了相应的swift变量，因此我现在尝试了以下操作:

I found the corresponding swift variables, so i now tried the following:

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
    guard metadataObjects?.count ?? 0 > 0 else {
        return
    }
    guard let metadata = metadataObjects.first as? AVMetadataMachineReadableCodeObject, let code = metadata.stringValue else {
        return
    }
    let big5encoding = String.Encoding(rawValue: CFStringConvertEncodingToNSStringEncoding(CFStringEncoding(CFStringEncodings.big5.rawValue)))
    print("Big5 encoded String: " + (String(data: code.data(using: .nonLossyASCII)!, encoding: big5encoding) ?? "?"))
}

输出:Big5 encoded String: \326\367\322\263\270\305\277\366

如何获得预期的输出Big5 encoded String: 主页概况

更新2:

看来我的QR码包含一些损坏的数据，所以我创建了一个新的Code，这次的内容绝对是Big5编码的String(Android应用正确读取了它).内容是傳統

It seems that my QR-Code contained some corrupt data, so i created a new Code, this time the content is definitely a Big5 encoded String (Android App reads it correctly). The content is 傳統

当我使用iOS应用程序扫描此代码时，metadata.stringValue返回日文字符串ｶﾇｲﾎ

When I scan this code with my iOS app, metadata.stringValue returns the japanese String ｶﾇｲﾎ

这到底是怎么回事?

推荐答案

CFStringEncodings 在Swift 3中被定义为枚举值:

CFStringEncodings are defined as enumeration values in Swift 3:

public enum CFStringEncodings : CFIndex {

    // ...    
    case big5 /* Big-5 (has variants) */
    // ...    
    case big5_HKSCS_1999 /* Big-5 with Hong Kong special char set supplement*/
    // ...    
}

所以你必须转换

CFStringEncodings -> CFStringEncoding -> NSStringEncoding -> String.Encoding

示例:

let cfEnc = CFStringEncodings.big5
let nsEnc = CFStringConvertEncodingToNSStringEncoding(CFStringEncoding(cfEnc.rawValue))
let big5encoding = String.Encoding(rawValue: nsEnc) // String.Encoding

然后big5encoding可用于在String和(NS)Data之间进行转换.

Then big5encoding can be used for conversion between String and (NS)Data.

在您的情况下，您有一个字符串，其中每个unicode标量对应于 Big5编码的字节.然后，下面的方法应该起作用:

In your case you have a string where each unicode scalar corresponds to a byte of the Big5 encoding. Then the following should work:

// let code = "\u{00D6}\u{00F7}\u{00D2}\u{00B3}\u{00B8}\u{00C5}\u{00BF}\u{00F6}"
let bytes = code.unicodeScalars.map { UInt8(truncatingBitPattern: $0.value) }
if let result = String(bytes: bytes, encoding: big5encoding) {
    print(result)
}

或者，使用ISO Latin 1编码映射的事实 Unicode代码将U + 0000 .. U + 00FF指向字节0x00 .. 0xFF:

Alternatively, using the fact that the ISO Latin 1 encoding maps the Unicode code points U+0000 .. U+00FF to the bytes 0x00 .. 0xFF:

if let data = code.data(using: .isoLatin1),
    let result = String(data: data, encoding: big5encoding) {
    print(result)
}

这篇关于如何在iOS上的Swift中使用Big5编码的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！