Strip Emoji (NSString)

emoji.m

#include <unicode/utf8.h>
// This only covers two of the common Emoji ranges, but the Emoji character set is broken
// up across seven different regions.
@implementation NSString (StripEmoji)
- (NSString *)stringByRemovingEmoji {
	NSData *d = [self dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:NO];
	if(!d) return nil;
	const char *buf = d.bytes;
	unsigned int len = [d length];
	char *s = (char *)malloc(len);
	unsigned int ii = 0, oi = 0; // in index, out index
	UChar32 uc;
	while (ii < len) {
		U8_NEXT_UNSAFE(buf, ii, uc);
		if(0x2100 <= uc && uc <= 0x26ff) continue;
		if(0x1d000 <= uc && uc <= 0x1f77f) continue;
		U8_APPEND_UNSAFE(s, oi, uc);
	}
	return [[[NSString alloc] initWithBytesNoCopy:s length:oi encoding:NSUTF8StringEncoding freeWhenDone:YES] autorelease];
}
@end

The heart emoji is an interesting one: I think it's an image used for a glyph that isn't traditionally in the emoji range.

Support for additional ranges can be added fairly easily (lines 15, 16), however!