一文字づつ区切る

NSStringEnumerationByComposedCharacterSequencesを用いる。

        NSString *string= @"ハローﾜｰﾙﾄﾞ🗾";
        
        NSMutableArray *list = [NSMutableArray array];
        
        [string enumerateSubstringsInRange:NSMakeRange(0,string.length)
                                                   options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString * _Nullable substring, NSRange substringRange, NSRange enclosingRange, BOOL * _Nonnull stop) {
                                                       [list addObject:substring];
                                                   }];
        for (NSString *sub in list) {
            NSLog(@"%@", sub);
            for (int i=0;i<sub.length;i++) {
                NSLog(@"%04x", [sub characterAtIndex:i]);
            }
                  
        }