Making a UIButton a % of the screen size

Question

I noticed certain button sizes look great on one the iPhone 5 simulator but do not look as good on the iPhone 6 simulator and this is because the heights or constraints that

Answer 1

You can't set a constraint to be 40% of the screen height. However, if the button always has a 20px leading and trailing to the superview you could use that width and set an aspect ratio height.

Another way could be to use UIScreen.mainScreen().bounds.size.height * 0.4 for your button height.

A third way is to use the button's superview to set the height. Assuming that your button is a direct child of a UIViewController's view: view.bounds.size.height * 0.4.

There's probably a bunch of other ways to do this as well but none of them will involve setting the height to an actual percentage as far as I'm aware.