I heard if you leave a phone plugged in for too long after it's fully charged it messes up the battery. With smart chargers it stops charging once the battery is 100% charged. Do iphones have smart chargers? Will anything happen to my phone if I leave it plugged in all night?
The charger isn't any smarter than any other one. It won't hurt to leave it in overnight. My little Samsung has a built in circuit that kicks off the charger to the battery connection once the battery is fully charged. Almost every new phone made does too. Some older phones will ~cook~ the battery when left on too long though.
