Question: I want to reduce and increase the font size of the text in a UILabel based on the screen size. I'm trying to build for iPhone 5s to iPad Pro screen size (if thats possible). The labels are in a vertical stack view

Answer: 
You can easily do that by changing the Autoshrink property of the label from its default value of Fixed Font Size to Minimum Font Scale.

Here I have attached an image to do that:

[![enter image description here](https://i.stack.imgur.com/VyAeU.png)](https://i.stack.imgur.com/VyAeU.png)
To achieve this:

1. click on the label and go to the attributes pane
2. change the "lines" to 0
3. In autoshrink click on minimum font size and set it to about half the size of your main font or a much smaller font