my iphone 5 (ios8.3) is heating up

Greetings kamran.pk,

It seems you are concerned about the operating temperature of your iPhone. The following article provides helpful information which may help:

Keeping iPhone, iPad, and iPod touch within acceptable operating temperatures - Apple Support

Use iOS devices where the ambient temperature is between 0º and 35º C (32º to 95º F). Low- or high-temperature conditions might cause the device to change its behavior to regulate its temperature. Using an iOS device in very cold conditions outside of its operating range may temporarily shorten battery life and could cause the device to turn off. Battery life will return to normal when the device is brought back to higher ambient temperatures.

Store the device where the temperature is between -20º and 45º C (-4º to 113º F). Don’t leave the device in your car, because temperatures in parked cars can exceed this range.

When using the device or charging the battery, it is normal for it to get warm. The exterior of the device functions as a cooling surface that transfers heat from inside the device to the cooler air outside.

Higher ambient temperature conditions and activities that may cause the device to alter performance and behavior include:

• Leaving the device in a car on a hot day.
• Leaving the device in direct sunlight for an extended period of time.
• Using certain features in hot conditions or direct sunlight for an extended period of time, such as GPS tracking or navigation in a car, or playing a graphics-intensive game.

If the interior temperature of the device exceeds the normal operating range, the device will protect its internal components by attempting to regulate its temperature. If this occurs, you may notice the following:

If the device exceeds a certain temperature threshold, it will present a temperature warning screen similar to this:

• The device stops charging.
• The display dims or goes black.
• In navigation:

  The device will present this alert and turn off the display: "Temperature: iPhone needs to cool down."

  • Navigation will continue to provide audible turn-by-turn directions. When approaching a turn, the display will illuminate to guide you through the turn.
  • To return the device to normal operation, press the Home Button and slide to unlock. If the device has cooled down enough, you can continue normal usage.
• Cellular radios will enter a low-power state. The signal may weaken during this time.
• The camera flash is temporarily disabled.

iOS 7 and later	iOS 6

To resume use of your device as quickly as possible, turn it off, move it to a cooler environment, and allow it to cool down.

Note (iPhone only): When this message appears, the device may still be able to make emergency calls.

Thank you for contributing to Apple Support Communities.

Best,

Bobby_D