Conversion helpers when handling IANACharSets.

NSStringEncodingExtensions.swift

extension NSString {
    static func ConvertIANACharSetNameToEncoding(name: String) -> NSStringEncoding? {
        let cf_encoding = CFStringConvertIANACharSetNameToEncoding(name)
        
        guard cf_encoding != kCFStringEncodingInvalidId else {
            return nil
        }
        
        return CFStringConvertEncodingToNSStringEncoding(cf_encoding)
    }
}

extension NSURLResponse {
    static var DefaultStringEncoding: NSStringEncoding { return NSUTF8StringEncoding }

    var suggestedEncoding: NSStringEncoding {
        get {
            guard let
                name = self.textEncodingName,
                encoding = NSString.ConvertIANACharSetNameToEncoding(name)
            else {
                return NSURLResponse.DefaultStringEncoding
            }
            return encoding
        }
    }
}