Will this ruin iPhone battery?

I try to charge my phone battery up to 100% every charge, but sometimes if I need to go somewhere and use my phone, ill disconnect it when it is around 20-80%, come back pretty soon, and connect it again. Does doing this ruin the battery?

Wrong category.

The iphone battery is pretty good from what i've ben told by my friends who have one.
It probably depends on what iphone you have. If you leave it plugged in when its at 100% it can wreak the battery though.