How can I convert a string, such as "iso-8859-1", to it's String.Encoding counterpart?

Question

After sending a HTTP request from Swift, I get a field in the response called textEncodingName.

I want to convert the data object I also received into a string containing its contents, and to do this, I'm using String(data: data!, encoding: .utf8). This works most of the time, because most websites are UTF-8 encoded. But with, for example, https://www.google.co.uk, the response.textEncodingName == "iso-8859-1".

I guess other websites would use even more obscure encodings, so my question is this: how can I find the right encoding to convert my data object to the correct string.

Answer 1

You can simply try String.Encoding.windowsCP1250 for iso-8859-1. Please refer https://en.wikipedia.org/wiki/Windows-1250

String(data: data, encoding: .windowsCP1250)

OR..

I found a few steps that will take you from the textEncodingName to the corresponding String.Encoding value:

let estr = "iso-8859-1"
let cfe = CFStringConvertIANACharSetNameToEncoding(estr as CFString)
let se = CFStringConvertEncodingToNSStringEncoding(cfe)
let encoding = String.Encoding(rawValue: se)

This is largely based on the documentation for URLResponse.textEncodingName:

You can convert this string to a CFStringEncoding value by calling CFStringConvertIANACharSetNameToEncoding(:). You can subsequently convert that value to an NSStringEncoding value by calling CFStringConvertEncodingToNSStringEncoding(:).

Here's an update that checks to see if the original text encoding string is valid or not:

let estr = "XXX"
let cfe = CFStringConvertIANACharSetNameToEncoding(estr as CFString)
if cfe != kCFStringEncodingInvalidId {
    let se = CFStringConvertEncodingToNSStringEncoding(cfe)
    let sse = String.Encoding(rawValue: se)
    print("sse = \(sse)")
} else {
    print("Invalid")
}