After watching WWDC 2016 session 420, Optimizing Web Content in Your App, I added "com.apple.webinspector.allow = YES" to the existing entitlements file.
Build & Run results in immediate crash. Reviewing the crash log reveals
Exception Type: EXC_CRASH (Code Signature Invalid)
Remove that row from the entitlement file and the app runs fine.
How can this be fixed, so that the app may connect to the Safari developer tools?
I have the same question. Did you ever got it to work?
I also just ran into this problem. Here Apple documents that this entitlement can be added, but then the app doesn't start anymore: https://webkit.org/web-inspector/enabling-web-inspector/
The only solution is to add the device UUID to your provisioning profile and distribute the development version.
The new technique is to enable an inspectable property on the JSContext and WKWebView.
https://webkit.org/blog/13936/enabling-the-inspection-of-web-content-in-apps/
-ch