Attachment for http://blog.hunch.se/post/1691630898/mapped-utf-8-utf-16-range-lookups-ftw

NSString-populateStdString.mm

#import <string>

@interface NSString (cpp)
- (NSUInteger)populateStdString:(std::string&)str
                  usingEncoding:(NSStringEncoding)encoding
                          range:(NSRange)range;
@end
@implementation NSString (cpp)
// Populate a std::string avoiding a double-copy
- (NSUInteger)populateStdString:(std::string&)str
                  usingEncoding:(NSStringEncoding)encoding
                          range:(NSRange)range {
  NSUInteger estimatedSize = [self maximumLengthOfBytesUsingEncoding:encoding];
  str.resize(estimatedSize);
  char *pch = (char*)str.data();
  NSUInteger usedBufferCount = 0;
  [self getBytes:pch
       maxLength:estimatedSize
      usedLength:&usedBufferCount
        encoding:encoding
         options:0
           range:range
  remainingRange:NULL];
  str.resize(usedBufferCount);
  return usedBufferCount;
}
@end

snippet.mm

std::string u8substr;
NSUInteger size = [nsstr populateStdString:u8substr
                             usingEncoding:NSUTF8StringEncoding
                                     range:highlightRange];
BOOL u8substrIsMutlibyte = size != str.length;