Magnetism for Artificial Gravity is a Terrible Idea
Magnetism, though might sound impressive for science-fiction, is actually a really terrible idea. Especially if the world is based on real-science, then magnetism is not the first choice.
For starters, magnetizing a piece of iron, the size of the ISS, would require the energy required to power a large city (that is kind of optimistic, it might take even more energy). I am not talking about electromagnets, I am talking about permanent magnets. Even hard iron can be magnetized with electricity to produce a permanent magnet, if the current is strong enough.
And furthermore, all metals can't be magnets, at least with the current understanding of physics. Spacecraft are mostly made of light elements like aluminum to minimize mass. There is a reason why the ISS and even the Space Shuttle are made of aluminum and not iron. Even with advanced technology, you would want to minimize the payload weight as much as possible, so that they can reach space easily. Another reason why most spacecraft are compact.
And anything metal would stay in position.
That is merely an assumption that rises from the fact that we live on a large planet, which exerts enough gravity to make some things feel heavier than others. Since metals generally have a high density, on Earth, they feel "heavy" and therefore, they stay in place.
However, in the vacuum of space, there is virtually nothing to exert any substantial gravity on the metals. So, iron would be virtually weightless in the microgravity environments of space. This means that your Magnetic base can be easily budged from its place by a slow impact.
However we haven't started with the worst problem yet.
Magnetism as artificial gravity has been suggested in multiple sci-fi books (such as Tintin-Explorers on the Moon), but in reality, magnetism only exerts a force on your exterior, and not on the interior.
This means that blood will pool in the head and torso, which can result in light-headedness, and other symptoms.
Your astronauts will get easily tired as they have to constantly walk with strong magnetic clothes, which means that they are weighted down to the ground, a bit too hard.
I'd stick to rotating habitats and O'Neill cylinders.