Detect UI actions outside of main thread

Question

Note: This question is related to Warn on calls to UIKit from background threads but does not give an answer on two of the approaches below.

I have a problem where the a

Answer 1

Starting with Xcode 9 Apple integrated an Main Thread Checker in Xcode which is enabled by default if you run you app in with the Xcode debugger.

It can be disabled/enabled in the scheme configuration under the diagnostics tab.