What impact does simulated metrics have?

Question

When using .xib files what impact on your code/app does changing simulated metrics have? Or is it just for your benefit as a preview tool?

Answer 1

Watch WWDC 2015 Session 407 Implementing UI Designs in Interface Builder, they talked about Simulated Metrics

Inferred

Now, right now they are all saying inferred. Inferred just basically means use the context around me. We know we are inside a tab bar controller, we know that we're inside a nav controller so interface builder knows which bar to show.

Simulated Metrics

All of these metrics do not affect your actual application at runtime with one exception and that's the size simulated metric.

The size simulated metric will actually change the size of your view controller but generally you're going to put it into a view controller hierarchy which will resize it, but it's also helpful if you are creating free form view controllers, for example, and want to set your own size.