I've running the latest Xcode 9 GM (13 Sep 2017) and have set Hardware > Face ID > Enrolled in simulator as well as Deployment Target 11.0. However I'm getting error code -6 LAErrorTouchIDNotAvailable. 
Is there some setting I'm missing?
let myContext = LAContext()
let myLocalizedReasonString = "You are pretty"
var authError: NSError?
if #available(iOS 8.0, macOS 10.12.1, *) {
    if myContext.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &authError) {
        myContext.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: myLocalizedReasonString) { success, evaluateError in
            if success {
                print("// User authenticated successfully, take appropriate action")
            } else {
                 print(" // User did not authenticate successfully, look at error and take appropriate action")
            }
        }
    } else {
         print(" // Could not evaluate policy; look at authError and present an appropriate message to user")
    }
} else {
     print(" // Fallback on earlier versions")
}
Face ID does not work in the Xcode 9 GM due to a framework bug. Xcode 9.1 fixes this issue.
You can test your app in the iPhone 8 simulator and ensure it works correctly with Touch ID or run the Xcode 9.1 beta and test Face ID support there.
I think the iphone X simulator's faceID doesn't work at the moment, hopefully they will fix it soon...
https://forums.developer.apple.com/thread/86779
we could do a bug report to see if it speed things along :P https://developer.apple.com/bug-reporting
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