Some tips and tricks I have come across by running XCTest which I thought might be helpful

Print the accessibility tree

If you want to know which elements are there it is just as easy as put a breakpoint where you are having issues and run the following:

po print(XCUIApplication().debugDescription)

Element not found?

If an element is not found it is maybe because you configured any of its super views with an accessibility identifier.

Once a view has an accessibility identifier set then subviews will not be visible in the accessibility tree.

If they are not visible you will not be able to fetch them.

Clear the data of your app before running the tests

XCTest has a variable called launchArguments. You can pass an argument that your AppDelegate will be able to pick up on start (or any other part of your code)

On willFinishLaunchingWithOptionsjust query for this argument and if it is a XCTest then proceed to clean up your app:

#if DEBUG
  if ProcessInfo.processInfo.arguments.contains("XCTest") {
    // cleanup NSDocumentDirectory, disable animations etc...
  }
#endif

Tip: If you have problems with legacy code and table/collection views, try to reloadData