How to display Xcode code coverage when is not displaing?
Issue Resolve in Version 9.3, to get the code coverage Target -> Test -> Options -> CodeCoverage See image:
If you want to see the code coverage in the right side of the editor, make sure you have Show Code Coverage selected in the Editor drop down menu.
There was known bug on Apple side addressed missed code coverage for UI tests targets (https://openradar.appspot.com/24006783).
Xcode Version 9.3 beta (9Q98q) seems resolves issue as long as Debug executable not enabled in Test schema.
In Xcode build scheme editor Test -> Info tab -> Debugger make sure that checkbox Debug executable is unchecked.