How to "Update Frame" in Xcode 8

There is a new Update Frames button at the bottom of the canvas. Click the button to update the frames of the selected objects and their children on the Interface Builder canvas.

Source - https://developerinsider.co/whats-new-in-xcode-8/

In Xcode 8, storyboards have been greatly improved to make what you see on the screen exactly the same as what you would see on the device when you run your app. And even though frames might update as you move things, there's a new handy standalone button to the leftmost side of the button you have selected in your question (it looks like a refresh button).

Theres's a few more options as well:

• You can use the keyboard shortcut: Cmd + Opt + =

• You can also look for "Update Frames", by going to the toolbar and selecting Editor -> Resolve Auto Layout Issues -> Update Frames.