iPhone screen freezes.. How to solve it ?
Some iPhone 6 and 6 Plus users have found that their deviceâ€™s display becomes unresponsive when using apps. The problem has been reported on phones running iOS 9.3.1 and iOS 9.3.2, and has been known to occur multiple times a single day.
Use the lock button to turn the screen off and on again.
Hold down the Sleep/Wake and Home buttons until you see the Apple logo appear to reset your iPhone.
Factory reset and restore your device as a new phone, or restore it from a backup.
If none of the aforementioned workarounds fixes the problem, consider contacting Apple or going to an Apple Store. The problem may be with the hardware, not the software.