How to Fix Expected Unqualified ID in My iOS Card Game

I’m currently building an iOS card game app using Objective-C++, and I ran into a rather frustrating issue that took me a while to diagnose. The error was vague at first, but with some digging, testing, and cleanup, I finally got to the bottom of it. I’m writing this blog post to explain the issue in plain language, how I fixed it, and some extra functionality I added along the way.

The Error

Error Message

error: expected unqualified-id
_LIBCPP_BEGIN_NAMESPACE_STD

This message came out of nowhere when I tried to include the following line in Pack.hpp:

#include <array>

Everything had been working fine earlier, so it was both surprising and frustrating. After digging into the error logs, I saw that the problem originated from the C++ standard library header <array>, which was included in Pack.hpp. So what was the real issue?

What’s Happening?

This isn’t a bug in <array> it’s a conflict between Objective-C++ and the C++ standard library. Specifically, it’s often caused by importing Objective-C system headers (like #import <Foundation/Foundation.h> or #import <UIKit/UIKit.h>) before or within C++ headers. These headers define macros and symbols that mess with the STL includes.

In my case, some Objective-C headers must have crept into my Card.hpp or Pack.hpp files or were indirectly included by them and that interfered with <array>.

The Fix

To resolve this, I carefully reviewed all headers and did the following:

Replaced old-style C headers:

#include <stdio.h>   // ❌ old-style; risky in C++

with:

#include <cstdio>    //  safe in C++

Cleaned out Objective-C imports:

• Removed any direct or indirect Objective-C headers from .hpp files.
• Ensured that headers like Foundation/Foundation.h or UIKit/UIKit.h are only ever included in .mm files.

Update Clean and Functional Code

Card.hpp

#ifndef Card_hpp
#define Card_hpp

#include <iostream>
#include <string>
#include <cstdio>

class Card {
public:
    static constexpr const char* const RANKS[] = {
        "Two", "Three", "Four", "Five", "Six", "Seven", "Eight",
        "Nine", "Ten", "Jack", "Queen", "King", "Ace"
    };
    static constexpr const char* const SUITS[] = {
        "Spades", "Hearts", "Clubs", "Diamonds"
    };

    Card();
    Card(const std::string& rank_in, const std::string& suit_in);

    std::string get_rank() const;
    std::string get_suit() const;
    bool is_face() const;

private:
    std::string rank;
    std::string suit;
};

bool operator<(const Card& lhs, const Card& rhs);
bool operator>(const Card& lhs, const Card& rhs);
bool operator==(const Card& lhs, const Card& rhs);
bool operator!=(const Card& lhs, const Card& rhs);

std::string Suit_next(const std::string& suit);
std::ostream& operator<<(std::ostream& os, const Card& card);

#endif

Pack.hpp

#ifndef Pack_hpp
#define Pack_hpp

#include "Card.hpp"
#include <array>
#include <string>

class Pack {
public:
    Pack();
    void shuffle();
    Card deal_card();

private:
    static const int PACK_SIZE = 312;
    std::array<Card, PACK_SIZE> cards;
    int next;
};

#endif

Additional Practice Functionality

Once the error was resolved, I added some features to improve gameplay mechanics and test the card-dealing logic.

Pack.cpp – Shuffle and Deal Logic:

#include "Pack.hpp"
#include <random>
#include <algorithm>

Pack::Pack() : next(0) {
    // For testing, just cycle through some dummy cards
    int suitIndex = 0, rankIndex = 0;
    for (int i = 0; i < PACK_SIZE; ++i) {
        cards[i] = Card(Card::RANKS[rankIndex], Card::SUITS[suitIndex]);
        rankIndex = (rankIndex + 1) % 13;
        if (rankIndex == 0) suitIndex = (suitIndex + 1) % 4;
    }
}

void Pack::shuffle() {
    std::random_device rd;
    std::mt19937 g(rd());
    std::shuffle(cards.begin(), cards.end(), g);
    next = 0;
}

Card Pack::deal_card() {
    if (next < PACK_SIZE) {
        return cards[next++];
    }
    throw std::out_of_range("No more cards to deal.");
}

Suggested Next Exercises:

Here are some enhancements I’m planning to work on next to level up this card engine:

• Implement reset_pack() to reshuffle and reset.
• Track dealt card statistics (e.g., how many Queens have been dealt).
• Write unit tests for card comparison.
• Implement basic AI logic to simulate a computer opponent.
• Add jokers or support multiple decks with flexible rules.

Final Thought

This error really threw me off because it came from such an innocuous place #include <array> and the message didn’t give much away. But the real issue was rooted in mixing Objective-C headers with C++ STL, something that’s especially sensitive when using Objective C++.

Lesson learned: Keep Objective-C and C++ code strictly separated unless you’re inside .mm files, and be super cautious with standard library includes. Clean header hygiene goes a long way when working in a hybrid project like this.