iOS 字元串數字中整數位，每三位添加一個逗号

- (NSString *)insetDouhao:(NSString *)str{
    NSString *intStr;
    NSString *floStr;
    if ([strcontainsString:@"."]) {
        NSRange range = [strrangeOfString:@"."];
         floStr = [str substringFromIndex:range.location];
         intStr = [str substringToIndex:range.location];
    }else{
        floStr = @"";
        intStr = str;
    }
    if (intStr.length <=3) {
        return [intStrstringByAppendingString:floStr];
    }else{
        NSInteger length = intStr.length;
        NSInteger count = length/3;
        NSInteger y = length%3;

        NSString *tit = [intStrsubstringToIndex:y] ;
        NSMutableString *det = [[intStrsubstringFromIndex:y] mutableCopy];

        for (int i =0; i < count; i ++) {
            NSInteger index = i + i *3;
            [det insertString:@","atIndex:index];
        }
        if (y ==0) {
            det = [[det substringFromIndex:1]mutableCopy];
        }
        intStr = [tit stringByAppendingString:det];
        return [intStrstringByAppendingString:floStr];
    }
}