Unable to determine simulator device to boot. - Xcode

问题

I just downloaded Xcode 6 & played with it a bit.

After switching back to previous version of Xcode and running in simulator, I keep getting this error.

Unable to determine simulator device to boot.

How do we resolve this?

Thanks in advance.

回答1:

Make sure you have only one iOS Simulator instance running in the Dock.

回答2:

There was a simple answer to this for me:

Open the simulator via Xcode -> Open Developer Tool -> iOS simulator (even if it can't launch, the app will be open).
With the simulator app open, go to Hardware -> Device -> Manage Devices.
Add any missing simulators with the plus button (all of mine were missing for some reason).

回答3:

I've faced same issue and solved by below steps:

1) Move xcode6-beta into application folder

2) Restart mac and open xcode6-beta from application folder.

回答4:

I had the same problem when running from Xcode 6 beta selecting iPhone 5s. If I choose iPhone 5 or "resizable iPhone" then my app launches fine.

回答5:

You will not see the profiles of simulator without a rebooting of OS X.I added simulator for many times,when the rebooting finished, it shows on the device list under the simulator bar. I think this is a bug of Xcode 6 Beta

回答6:

I think you have 2 simulator running in the dock. Please close another one simulator and run the project again. It might helpful for you.

回答7:

In my case I had such a message just because the simulated device was still booting (longer than usually, I guess). Xcode 7.2. (This is not actually an answer to this specific question, but I came here googling the message in the title, so I am writing my note here for if someone else gets the same case as I did)