'iostream' file not found Xcode

Whenever I try to use Xcode 11 to build C++ programs and type in the line:

#include <iostream>

An error saying "'iostream' file not found shows up. The library I am using is libc++ and not libstdc++.

Other people dont seem to encounter this problem so I do not know what is going on.

#include <iostream>
using namespace std;

int main()
{
    cout << "Hey, this really works!" << endl;
}