报错信息：
Failed to find or create execution context for description ‘<IBCocoaTouchPlatformToolDescription: 0x7fe0ddceada0> System content for IBCocoaTouchFramework-ElevenAndLater <IBScaleFactorDeviceTypeDescription: 0x7fe0dd8606b0> scaleFactor=2x’. These intermediate objects were non-nil:
解决方法：
在终端里
sudo killall -9 com.apple.CoreSimulator.CoreSimulatorServiceSet the correct Xcode path
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
xcrun simctl erase all
