如何用代码Swift.2调整表的高度

I've made it so a textfield is always on top of the keyboard (like in the messages app, whatsapp...) but my problem is that this poses the table above it up too because everything is in a scrollview. How can i make it so the table resizes so it fits in the space between the keyboard and top of the screen. I've made it so a textfield is always on top of