How to change the iOS Simulator "window background color" (Full Screen, Xcode 10, Mojave, Dark Mode)

Question

Mojave (macOS 10.14) is great.
Xcode 10.0 (10A254a) is great.
Dark Mode is great.

What is not so great, unless I'm missing something, is this ugly gray background of the iOS simulator window (when in full screen):

Any idea on how to change that color?

Answer 1

I have the answer you seek.

Boot into recovery mode (Cmd+R while booting) and then open the Terminal.

1. cd /Volumes/Macintosh\ HD //if your drive is named something different, replace accordingly

2. csrutil disable //disables System Integrity Protection

3. mkdir AppleInternal //activates testing and custom commands in Apple apps, including Simulator

4. csrutil enable //re-enable System Integrity Protection

5. reboot //back to regular environment

Now there's an "Internal" menu in the Simulator. In here, you can change loads of settings including the window's background color. It uses the regular OS X colour picker so you can even choose a hex code.

Answer 2

If anybody still struggles with this here is somewhat a solution: toggle "Show Device Bezels" in the window menu of the simulator will do the trick. However this needs to be done each time the simulator is started....

Answer 3

The correct answer to this (I'm on Catalina 10.15.7): Change your desktop background to the desired color. The simulator adapts to the color with a different opacity (or alpha?!) value when in fullscreen mode.