When this error occurs in Xcode, check if your project’s build settings are trying to launch with an older version of Simulator.
iOS Simulator could not find the SDK. Could not find the SDK. You may need to reinstall the SDK.
In my case, the issue was that I was trying to launch with “iPhone 5.0 Simulator” when I should have been launching with “iPhone 6.0 Simulator”.
That’s all from the Gemba.
【Reference】Xcode4 - src’s wiki