Open Radar

 
Duplicate of 25962752 (Open)

Area:
TouchID

Summary:
Our iOS application uses Touch ID as an alternative to typing in a PIN to unlock access to the app. Since adding this feature, we have received reports from users about the Touch ID interface not being displayed reliably. We have tried numerous things to make the display of the Touch ID interface more reliable:

 1. Ensuring that a view controller is on screen before using LAContext to evaluate the LAPolicyDeviceOwnerAuthenticationWithBiometrics policy
 1. Waiting on receipt of UIApplicationDidBecomeActiveNotification before using LAContext
 1. Using dispatch_async() to delay the use of LAContext until the next run loop iteration after receiving UIApplicationDidBecomeActiveNotification
 1. Automatically retrying invocations of -evaluatePolicy:localizedReason: when receiving the -1004 "User interaction is required" error
 1. Adding a button to allow users to request Touch ID when it fails to display automatically

Nothing has fully resolved the problem so that Touch ID is displayed reliably. Even the case of user interaction through the button does not satisfy the user interaction requirement.

Steps to Reproduce:
The reproduction is unknown.

Expected Results:
When the application is in the active state with a view controller on screen, we expect that sending -evaluatePolicy:localizedReason: to an instance of LAContext will result in the Touch ID interface being displayed if the user has Touch ID enabled and configured on their iOS device.

Actual Results:
Most user reports read like this:

> Using Touch ID to unlock the app worked for a while, but then it stopped being displayed. Tapping the button to display it has no effect.

Our log files from the app show that the following error occurs in these circumstances:

Error Domain=com.apple.LocalAuthentication Code=-1004 "User interaction is required." UserInfo={NSLocalizedDescription=User interaction is required.}


Version:
iOS 8.4, iOS 9.1, iOS 9.2, iOS 9.2.1, iOS 9.3, iOS 9.3.1, iOS 9.3.2

Notes:
A reproduction has yet to be determined. When users see it, they tend to say that it stops working until they update to a newer version. Then, it works for a while until stopping again.

Configuration:
iPhone 5s, iPhone 6, iPhone 6s, iPad Air 2