How to convert std::string to NSString?

Get c-string out of std::string for conversion:

NSString *errorMessage = [NSString stringWithCString:REALM.c_str()                                    encoding:[NSString defaultCStringEncoding]];

Firstly, you've got to be using Objective-C++ for this to work in the slightest; easiest way to ensure that is rename all your *.m files to *.mm

By far the most usable (non-deprecated) manual way of getting a C++ std::string into an NSString is with:

std::string param; // <-- inputNSString* result = [NSString stringWithUTF8String:param.c_str()];NSString* alternative = [[NSString alloc] initWithUTF8String:param.c_str()];

This will work in most cases - and if you're not doing specific encoding detection and conversion, UTF-8 is going to give you a good result for having non-latin characters 'just work.'

If you're making a bigger app, or you're not the only one working on it, however - you'll probably want something that's easier to apply.

Adapted from cocoa-dev mailing list archives

@interface NSString (cppstring_additions)+(NSString*) stringWithwstring:(const std::wstring&)string;+(NSString*) stringWithstring:(const std::string&)string;-(std::wstring) getwstring;-(std::string) getstring;@end@implementation NSString (cppstring_additions)#if TARGET_RT_BIG_ENDIANconst NSStringEncoding kEncoding_wchar_t = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingUTF32BE);#elseconst NSStringEncoding kEncoding_wchar_t = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingUTF32LE);#endif+(NSString*) stringWithwstring:(const std::wstring&)ws{    char* data = (char*)ws.data();    unsigned size = ws.size() * sizeof(wchar_t);    NSString* result = [[NSString alloc] initWithBytes:data length:size encoding:kEncoding_wchar_t];    return result;}+(NSString*) stringWithstring:(const std::string&)s{    NSString* result = [[NSString alloc] initWithUTF8String:s.c_str()];    return result;}-(std::wstring) getwstring{    NSData* asData = [self dataUsingEncoding:kEncoding_wchar_t];    return std::wstring((wchar_t*)[asData bytes], [asData length] / sizeof(wchar_t));}-(std::string) getstring{    return [self UTF8String];}@end

With that in-place (and appropriately #imported) you can now:

NSString* result = [NSString stringWithstring:param];string convertedBack = [result getstring];

And the same for std::wstring, which is more than handy.

NSString* mystring = [NSString stringWithUTF8String:stdstring.c_str()];