Fixed some "Unknown" responses on iOS 9.2.

[brianhv]

Returns LNPasscodeStatusDisabled when SetItemAdd returns errSecAuthFailed, as it seems to do in iOS 9.2.

[liamnichols]

Hey,

Thanks for the PR. I'm not really sure what to do here because errSecAuthFailed can be called due to various unrelated reasons too. (i.e if there are just generic keychain issues).

Problem is that if we use this check that we could get false negatives where the passcode is not in fact disabled but we think it is. I guess it's better than us thinking its enabled when its not but i'm not too sure if its the best way to do things.

I guess it was a hack implementation from the start :/

Does iOS 9.2 exclusively use errSecAuthFailed over errSecDecode or is it just some scenarios?

[brianhv]

I don't have an answer to your question. It's happening consistently enough for me that this patch is an improvement for my purposes, and it was enough for me to offer it for others. I would totally understand a need for further research before accepting it into the master branch though.