Q:

Proportional Height constant is 0.0

When I have a fixed height and I make an outlet to my ViewController and print out that value, I get the correct height. When I delete that constant, make the height proportional and reconnect to the outlet and print the value, it says 0.0. I clearly see that is bigger than 0.0, rather 50.0. How can this be?

A:

Because you're printing the value of Height constant and not the height itself. 
So when you don't have height constraint to your control i.e. when you remove the fix height, it will be 0.0 always. Because it's absent.

