Swift version: 5.0
Apple frequently leaves debugging messages in iOS simulator builds, which is both good and bad: it's good because sometimes the information is useful, but it's bad because more often than not it just causes unnecessary worries.
You can ignore this particular error if you want to; it's nothing to do with your code, it's just Apple's logging code pointing out that you have enabled a particular setting in the simulator.
If you desperately want to stop this error from appearing, open the Simulator on your Mac, go to the Debug menu, then choose Graphics Quality Override > Device Default. This message usually appears when you have it set to High Quality, which may cause performance degradation.
Alternatively, go to the Hardware menu and choose Erase All Content And Settings to clear the simulator back to its defaults.
Available from iOS 9.0
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.