This iPhone (Model A1863, A1905, A1906, A1907) is running iOS 11.4 (15F79)

iOS 11.4(15F79) (15F5037c)真机包，不需要在更新xcode，直接下载后在访达前往 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport 然后载入就行。