Some owners of the iPhone 6s handset have had problems with the device continually shutting down, the reason for this is apparently to do with the battery on the device.
Owners of the handset were reporting that their iPhone 6S would shut down even when they had 50% battery life left, Apple has issued the following statement about the issue.
“Apple has determined that a very small number of iPhone 6s devices may unexpectedly shut down. This isn’t a safety issue and only affects devices within a limited serial number range that were manufactured in September and October 2015.”
The issue apparently only affects a small number of devices, if you have had this problems with your iPhone 6S then you should contact Apple to get the issue resolved.