When it comes to simple yet useful features, iOS is packed. The Accessibility section of Settings is full of gold nuggets. Here's one that more and more people are finding useful.
When an email, message or phone call is received, it usually triggers some sort of audio alert as well as the vibration motor. In most cases, this works really well, but not always. There are times when noises just aren't acceptable or loud environments make it may be difficult to hear these alerts and alarms. This tip will allow you to use our LED flash as an alert trigger.
To enable this feature, go to Settings > General > Accessibility and switch on "LED Flash for Alerts".
With this option enabled, your LED flash will, well, flash each time you receive an email, message or phone call (even when the mute switch is engaged).