How to always get english string from NSError? - ios

Question

I've got an iOS application that is designed with English-only strings. When running on an iOS device that is using another language for display (i.e. Settings/General/Language/iPhoneLanguage is something non-English) I would like to also show system errors in English since my font can't display non-english characters at the moment.
Is there a way to always get the english error message from NSError? Or to lookup the english error string in the system somehow manually?

Answer 1

After digging around I found a potential workaround.
First, it turns out that in most cases, iOS is returning English strings from [myNSError localizedDescription] when I'm running on a system that has the region set to, say, France, with the language set to, say, French. I believe this is because I have CFBundleDevelopmentRegion set to "en" in my info.plist. This is what I wanted to happen since I am trying to build an app that runs fully in English everywhere (for the moment).
However, in some cases, like if you try to buy something in the app and the network is off (this is my most reliable repro case), I will get NSErrors that return a localized error from [myNSError localizedDescription]. In this case: "Connexion à l’iTunes Store impossible."
When I get an error like this, a workaround that kinda works is to create an NSError manually using the domain and error code from the original. If you then ask it for the localizedDescription it will give you one in English, but it seems to be more general. In this case: "The operation couldn’t be completed.". What appears to be happening is that the system is filling in more detailed errors using the local language.
string GetEnglishLocalizedDescription(NSError *originalError)
{
if(originalError == nil)
{
return "";
}
else
{
NSString *originalNSErrorString = [originalError localizedDescription];
string originalUtf8String = originalNSErrorString == nil ? "" : [originalNSErrorString UTF8String];
// If we have a character outside of the US Ascii range
// Our font won't display it properly and this is probably
// a localized description
// https://tools.ietf.org/html/rfc3629
bool isUSAscii = true;
for(uint8_t c : originalUtf8String)
{
if(c > 0x7F)
{
isUSAscii = false;
break;
}
}
if(!isUSAscii)
{
// Has non-US Ascii characters, probably localized, get the standard error instead
NSString *englishNSErrorString = [[NSError errorWithDomain:originalError.domain code:originalError.code userInfo:nil] localizedDescription];
string englishUtf8String = englishNSErrorString == nil ? "" : [englishNSErrorString UTF8String];
return englishUtf8String;
}
else
{
return originalUtf8String;
}
}
}
Then, the trick is to figure out when you want to do this because you can't really tell in an obvious way that you got an error in the local language. In my case, I can just look for characters that my font can't display and convert it. If my font can display it, I guess I'm OK displaying it since either:
a) it is in english and the whole app is so nothing surprising or
b) it is actually localized just happens to be a string that has characters that are all also English characters. In this case, presumably the user will be able to read it in their local language.
One final gotcha using the code/algorithm above: It turns out the English error messages that Apple uses don't stick to the normal ASCII character set. They will use the fancy apostrophe in Unicode as opposed to the ASCII "'". So, the code above will think that is a "localized" message. Unclear what other characters they do this with. So this isn't really a full solution. It does solve the original question of "How do I always retrieve an English error message", but it doesn't fully solve my problem since i have no idea how to build a font that will even show all English error messages. Sigh.
Still have to decide the best approach here, but it is something.