How to use touchIDAuthenticationAllowableReuseDuration - ios

Question

I am authenticating a user via LAContext when an app is launching or when will enter foreground. If a device was locked then the user will be asked twice to authorize himself. To avoid that behavior, I set context.touchIDAuthenticationAllowableReuseDuration value to 240 but It doesn't work as expected. The user still has to authorize himself twice.
What I am doing wrong?
import LocalAuthentication
class AccessControl {
internal var context = LAContext()
private var policy: LAPolicy = .deviceOwnerAuthentication
private var reason: String = NSLocalizedString("auhenticationLocalizedFallbackTitle", comment: "")
init() {
context.touchIDAuthenticationAllowableReuseDuration = 240
}
func evaluateUserWithBiometricsOrPasscode(success: #escaping () -> Void, error: #escaping () -> Void) {
guard context.canEvaluatePolicy(policy, error: nil) else {
error()
return
}
context.evaluatePolicy(policy, localizedReason: reason) { eStatus, eError in
DispatchQueue.main.async {
if eStatus {
success()
} else {
error()
}
}
}
}
}

Answer 1

You need to use the same LAContext object everytime to get that behaviour.
class AccessControl {
// MARK: - Singleton
public static let shared = AccessControl()
// Policy
private var policy: LAPolicy = .deviceOwnerAuthentication
// Reason
private var reason: String = NSLocalizedString("auhenticationLocalizedFallbackTitle", comment: "")
// Context
lazy var context: LAContext = {
let mainContext = LAContext()
if #available(iOS 9.0, *) {
// specify your interval
mainContext.touchIDAuthenticationAllowableReuseDuration = 60
}
return mainContext
}()
// Evaluate
func evaluateUserWithBiometricsOrPasscode(success: #escaping () -> Void, error: #escaping () -> Void) {
guard context.canEvaluatePolicy(policy, error: nil) else {
error()
return
}
context.evaluatePolicy(policy, localizedReason: reason) { eStatus, eError in
DispatchQueue.main.async {
if eStatus {
success()
} else {
error()
}
}
}
}
}
And calling this function like below: This will work for FaceID Authentication also.
AccessControl.shared.evaluateUserWithBiometricsOrPasscode(success: {
}) {
}