iOS 字符串转JSON去除特殊字符的方法（去除表情）

- (NSString*)removeEmoji:(NSString *)username {
    
    NSString *regex =
@"^[0-9.\u4e00-\u9fa5]+$";
    NSPredicate *predicate = [NSPredicate
predicateWithFormat:@"SELF MATCHES %@", regex];
    NSString *temp =
nil;
    
    for(int i =
0; i < [username length]; i++)
    {
        temp = [username substringWithRange:NSMakeRange(i,
1)];
        if ([predicate
evaluateWithObject:temp]) {
            NSLog(@"%@", temp);
            NSLog(@"This character is OK");
        } else {
            NSRange range =
NSMakeRange(i, 1);
            username = [username stringByReplacingCharactersInRange:range
withString:@" "];
        }
    }
    
    NSString *withoutEmojiUsername = [username
stringByReplacingOccurrencesOfString:@" "
withString:@""];
    
    return withoutEmojiUsername;
}