当运行Xcode时，程序显示
[Client] Updating selectors failed with: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service on pid 0 named com.apple.commcenter.coretelephony.xpc was invalidated." UserInfo={NSDebugDescription=The connection to service on pid 0 named com
这个错误时，说明是你开启了全局代理，而去访问局域网资源。
解决办法：关闭打印。在终端输入以下一句即可关闭打印。
xcrun simctl spawn booted log config --mode "level:off" --subsystem com.apple.CoreTelephony