This demo project uses the Keychain store, load and delete credentials. It works as expected with iOS 9 and on a device with iOS 10. But when the included tests are run with iOS 10 the OSStatus is -34018 which indicates a missing entitlement.
It is not clear why this status is returned. The unexpected status is returned when the SecItemDelete function is used. The expected results are noErr or errSecItemNotFound.
There appears to be a history of this status being returned unexpectedly with previous versions of iOS.
The included tests demonstrate the issue. Running tests with a device running iOS 10 appears to work. Running with an iOS Simulator with iOS 10 fails. The tests succeed with iOS 9 with the Simulator.
MIT
Brennan Stehling - @brennansv