Hello Türker AKPINAR,
In some instances, it can be expected for your iPhone to become warm.
"You might notice that your device feels warmer when you:
- Set up your device the first time
- Restore from a backup
- Wirelessly charge your device
- Use graphics-intensive or processor-intensive apps, games, or features, including augmented-reality apps
- Stream high-quality video
These conditions are normal, and your device will return to a regular temperature when the process is complete or when you finish your activity. If your device doesn't display a temperature warning, you can keep using your device."
If your iPhone, iPad, or iPod touch gets too hot or too cold includes this information along with recommended operating temperatures for your iPhone.
If you're receiving temperature warnings on the device when it's been used under normal conditions, we'd recommend reaching back out to Apple Support.
Regards.