XCode 7.3 Simulator Unable to Boot

Question

So I've been working on a project at work for a while and have been having no issues running the app in the simulator. Yesterday, when I tried running the application again, the simulator opens and has a black screen. Then a popup appears stating "Unable to boot the simulator."

I did my research and I searched around and tried the following solutions to no avail:

• restarting Xcode,
• trying different applications in simulator
• deleting Xcode and redownloading
• restarting Mac
• deleting derived data
• tried different simulator devices

For reference, I am running Xcode 7.3 and running MacOSX 10.11.6

Answer 1

Was able to fix the problem by rebooting into recovery mode (hold command+r). Open terminal and run

csrutil disable reboot

Went back into Xcode and ran the simulator.

Went back into revoery to enable what was disabled. Works fine now!

Answer 2

I had a similar problem. It disappeared after installing the latest Sierra macOS.

Answer 3

当模拟器在顶层菜单中启动时，单击模拟器 - >重置内容和设置...

Answer 4

I tried everything that this post and others suggest. Recovery mode 'csrutil' wasn't available for me, so I couldn't try that.

This is what had caused this issue in the first place, System Preferences -> Security & Privacy -> Apps downloaded from - This was set to 'Anywhere' changing this to 'Mac App Store and identified developers' fixed the issue for me.