Why my phone turn off
When I start Facebook, application it closes. Since i update to ios 11.2.1
Help me
When I start Facebook, application it closes. Since i update to ios 11.2.1
Help me
Try deleting the app.
Then do a forced restart for your model as indicated in the link and when the phone restarts reinstall the Facebook app.
If your iPhone, iPad, or iPod touch won't turn on or is frozen - Apple Support
Why my phone turn off