I have a bit of a tricky set up in my storyboard, I have a UIViewController that holds a UITableViewController. Within the UITableViewController I have several prototypecell
To go a little further on Dao's answer..
He is correct, you need to use UITableViewAutomaticDimension
Also, you need to ensure that you setup your constraints in a way that all of the content in the cell is constrained to the cells contentView. So your label will likely need constraints such as
Make sure that you set the UILabel to multiline (or lines = 0) and it should work.
If you are using the heightForRowAt delegate functions ensure you return UITableViewAutomaticDimension