Why are the leaves of my Peace Lily wilted and black?

If you have been watering it with -hard- tap water, then the damage may have been caused by the accumulation of minerals in the soil. Either replace the soil or use bottled water in abundance to rinse the soil.

Cold is a possibility, but I don't think that's what's caused this damage; given where you are, unless you've had freak weather conditions in your particular location, it seems the temperatures recently have not fallen below 20 deg C during the day.

What has caused it is direct sunlight. These plants do not like direct sunlight even indoors - outside it would be even more damaging, particularly as the plant has probably never experienced any direct sunlight in the whole of its life. Peace lily is a reliably good low light houseplant, so perfect for your apartment.

Trim off the damaged leaves at their bases, the plant will put out more quite happily. These plants do not like to dry out completely and do seem to require a fair amount of watering. That, though, does not mean you should leave it standing in water in an outer tray or container - empty that 30 minutes after watering. Water when the surface of the compost feels just slightly dry to the touch, and stand the plant away from heat sources such as radiators - the light from any window which does not admit sun, or get any direct sunshine on it other than possibly very early morning or very late in the day, would be the most useful.

That is cold damage. It was too cold outside for your plant, and the cold damaged the cells (by expansion > rupture).

That looks like a peace lily. Here's a good article on cold damage in peace lilies. From that article:

a study by members of the University of Florida's Environmental Horticulture department showed that peace lily can be damaged by temperatures from just above 32 degrees Fahrenheit to 59 degrees Fahrenheit.

The damage began at the leaf tips and spread inwardly, with soft, brown areas turning black and then drying up.

So it looks like (for a small plant like yours anyway), you want it only to be placed in temps above 60 degrees F. This person's peace lily has also had cold damage:

You can avoid this later, by keeping in mind that most houseplants came from warm climates, and don't like it much below room temperature, especially if they haven't adapted, and are used to warm temps.