Does overcharging an iPhone degrade its life? I often like to charge my iPhone for long periods at a time (like say when I'd get home I will just plug it into the charger regardless of how much battery there is left).

Will this spoil my phone by overcharging or will it in any way, degrade my phone?
An iPhone (in working order) stops charging when it reaches 100%, even if you leave it plugged in.  Or are you perhaps asking about a malfunctioning iPhone, where for some reason this cut-off is not working?