Error message every time while install ionic app to ios

Every time when I do this:

ionic run ios 

I’ll see the following error message:

[ 90%] SandboxingApplication
[100%] Install(lldb) Executing commands in '/tmp/fruitstrap-lldb-prep-cmds-'.
(lldb)      platform select remote-ios --sysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/*
  Platform: remote-ios
 Connected: no
  SDK Path: "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/*"
(lldb)      target create "/Users/qguo/phonegap/frontline-plus/platforms/ios/build/device/FRONTLINE Plus.app"
Current executable set to '/Users/qguo/phonegap/frontline-plus/platforms/ios/build/device/FRONTLINE Plus.app' (armv7).
(lldb)      script fruitstrap_device_app="/private/var/mobile/Applications/2160A4E3-E58F-4AED-863A-BEEE6F53A897/FRONTLINE Plus.app"
(lldb)      script fruitstrap_connect_url="connect://127.0.0.1:12345"
(lldb)      script fruitstrap_handle_command="command script add -s asynchronous -f fruitstrap_.fsrun_command run"
(lldb)      command script import "/tmp/fruitstrap_.py"
run
error: the platform is not currently connected
(lldb)

However, my app was installed successfully to my iPhone.
Does anyone know why this happens?

see Error when doing 'ionic run ios'