the program runs normally. Xcode opens StoryBoard and Xib prompts an internal error occurred. Editing functionality may be limited. The StoryBoard and Xib files in the previous project cannot be edited, and the new StoryBoard and Xib files cannot be edited. The project is normal on other computers, and I feel that my computer is poisonous. 
some solutions found on the Internet, such as restarting Xcode after clean, deleting DerivedData, restarting Xcode, and reinstalling Xcode, have all been tried, but to no avail.
< H1 > finally post the Log log: < / H1 >XCODE VERSION INFO:=
Version = 9.4.1 (9F2000)
Plugin Version = 14113
Beta Version = 0
OS Version = 10.13.5 (17F77)
=
ERROR:=
Encountered an error communicating with Interface Builder Cocoa Touch Tool. (Failure reason: Interface Builder CocoaTouchTool failed to launch): Failed to boot device IBSimDeviceTypeiPad2x (5E2445B3-FC87-42A2mura B00715A3335F, iOS 11.4, Shutdown) for context < IBCocoaTouchToolLaunchContext: 0x7f8a20deaa50 > toolName = Interface Builder CocoaTouchTool, description = < IBCocoaTouchPlatformToolDescription: 0x7f8a39ace8e0 > System content for IBCocoaTouchFramework-ElevenAndLater < IBScaleFactorDeviceTypeDescription: 0x7f8a2152e600 > scaleFactor=2x (Failure reason: Failed to boot IBSimDeviceTypeiPad2x (5E2445B3-FC87-42A2mura A202murB00715A3335F, iOS 11.4, Shutdown)): Unable to boot the Simulator. (Failure reason: launchd failed to respond.)
Error Domain=com.apple.InterfaceBuilder Code=-1 "Encountered an error communicating with InterfaceBuilder Cocoa Touch Tool." UserInfo= {NSLocalizedFailureReason=Interface Builder CocoaTouchTool failed to launch, NSUnderlyingError=0x7f8a2164f250 {ErrorDomain = NSPOSIXErrorDomain Code=60 "Operation timed out" UserInfo= {NSLocalizedFailureReason=Failed to boot IBSimDeviceTypeiPad2x (5E2445B3-FC87-42A2mura A202murB00715A3335F, iOS 11.4, Shutdown), NSLocalizedDescription=Failed to boot device IBSimDeviceTypeiPad2x (5E2445B3-FC87-42A2mura A202murB00715A3335F, iOS 11.4, Shutdown) for context < IBCocoaTouchToolLaunchContext: 0x7f8a20deaa50 > toolName = Interface Builder CocoaTouchTool, description = < IBCocoaTouchPlatformToolDescription: 0x7f8a39ace8e0 > System content for IBCocoaTouchFramework-ElevenAndLater < IBScaleFactorDeviceTypeDescription: 0x7f8a2152e600 > scaleFactor=2x, NSUnderlyingError=0x7f8a3be920e0 {ErrorDomain = NSPOSIXErrorDomain Code=60 "Operation timed out" UserInfo= {NSLocalizedFailureReason=launchd failed to respond., NSLocalizedDescription=Unable to boot the Simulator.}, NSLocalizedRecoverySuggestion=Please check Console.app for crash reports for "Interface Builder Cocoa Touch Tool" for further information., NSLocalizedDescription=Encountered an error communicating with Interface Builder Cocoa Touch Tool.}