It really depends on how it was wired before. But if the light is staying on, you have a hot connected to the fixture.

So how it works: hot is connected to the switch, then another wire connects from the switch to the fixture. When you flip the switch, the hot continues through the switch, to the fixture=on. When you turn the switch off, the current stops at the switch. The blacks in the box could be another circuit.

Typically here, a red is used to connect the switch to a light fixture and black is always hot. But wiring in Chicago is much different than other places.

In the future, always take a pic before unhooking any wires. Even if you can't figure out what to do, it helps others help you.

What’s most likely happened is the electrician pulled power from a device to the light and pulled a wire down to the switch. The black wire going to the white wire is bringing permanent power down to the switch to be controlled on the black wire up to the light while the white wire they had from the permanent power brought to the light box will be the neutral for the light. So you need to figure out which wire has power all the time and bring that to white of the opposite wire so that it can be switched again