libMobileGestalt MobileGestaltSupport.m:153: pid 1668 does not have sandbox access in Xcode console

Using Apache Cordova, in my case, I had the same issue, and after some deep searches, I found it was originally (and stupidly) due to Splashscreen.

Check/add these lines in your config.xml file :

<preference name="SplashMaintainAspectRatio" value="true" /><preference name="FadeSplashScreenDuration" value="300" /><preference name="SplashShowOnlyFirstTime" value="false" /><preference name="SplashScreen" value="screen" /><preference name="SplashScreenDelay" value="3000" /><preference name="AutoHideSplashScreen" value="true" /><feature name="SplashScreen">    <param name="ios-package" onload="true" value="CDVSplashScreen" /></feature>

And then my app worked like a charm. Hope this helps in your case.

After digging into it, I found that embedding a UIViewController -or any subclass of it- in a navigation controller is the main reason to show this error message.
I'm not sure what exactly makes the navigation controller show this message.

Edit 1:

After Xcode 9, I'm not seeing this issue anymore with new projects created in Xcode 9

Edit 2:

In Xcode 9, I saw the same error when working with CGRect.