How can I set CG_CONTEXT_SHOW_BACKTRACE environmental variable?

Question

I have three buttons in my view. After setting the cornerRadus in the viewDidLoad() : button.layer.cornerRadius = 20 I get the following error message in the lo

Answer 1

It's a bug in 9b5:
https://forums.developer.apple.com/thread/13683

File a RADAR with Apple.