How come my iPhone camera only works when it?

When i'm trying to use my back camera its just black and everytime i'm in cold weather it works. WHAT's WRONG WITH MY PHONE I NEED ANSWERS.

There could be water in the phone

As per special conditions iPhone is only operatable to full access in the following situations:

1.Operating temperature: 32° to 95° F
(0° to 35° C)
2.Non operating temperature: -4° to 113° F
(-20° to 45° C)
3.Relative humidity: 5% to 95% non condensing
4.Maximum operating altitude: 10,000 feet (3000 m)

EVEN AFTER HAVING THE POSITIVE SIDE IT DOES NOT WORK THEN CONTACT APPLE AS I HAVE NOT READANYTHING LIKE THIS IN MY WHOLE EXPERIENCE. SEARCHED FOR THIS EVEN VERY DIFFICULTLY. GOOD LUCH BUDDY I HOPE THIS Help.