المصادقة البيومترية

القياسات الحيوية باستخدام LocalAuthentication

import LocalAuthentication
let context = LAContext()
// One LAContext object drives a single auth attempt

التحقق من التوفر أولًا

import LocalAuthentication
func canUseBiometrics() -> Bool {
    let context = LAContext()
    var error: NSError?
    return context.canEvaluatePolicy(
        .deviceOwnerAuthenticationWithBiometrics,
        error: &error)
}

السياستان

import LocalAuthentication
// Biometrics only (no passcode fallback):
let strict = LAPolicy.deviceOwnerAuthenticationWithBiometrics
// Biometrics with passcode fallback:
let lenient = LAPolicy.deviceOwnerAuthentication
_ = (strict, lenient)

تقييم السياسة

import LocalAuthentication
func authenticate() async -> Bool {
    let context = LAContext()
    do {
        return try await context.evaluatePolicy(
            .deviceOwnerAuthentication,
            localizedReason:
                String(localized: "Unlock your account"))
    } catch {
        return false
    }
}

اكتشاف نوع القياسات الحيوية

import LocalAuthentication
func biometryLabel() -> String {
    let context = LAContext()
    _ = context.canEvaluatePolicy(
        .deviceOwnerAuthenticationWithBiometrics, error: nil)
    switch context.biometryType {
    case .faceID:  return "Face ID"
    case .touchID: return "Touch ID"
    case .opticID: return "Optic ID"
    default:       return "Passcode"
    }
}

معالجة الأخطاء

import LocalAuthentication
func describe(_ error: Error) -> String {
    guard let la = error as? LAError else { return "failed" }
    switch la.code {
    case .userCancel:        return "cancelled"
    case .biometryLockout:   return "locked out"
    case .biometryNotEnrolled: return "not set up"
    default:                 return "failed"
    }
}

سلسلة استخدام Face ID

// Info.plist:
// NSFaceIDUsageDescription =
//   "We use Face ID to unlock your saved passwords."
let required = "NSFaceIDUsageDescription is mandatory"
_ = required

تخصيص ورقة المصادقة

import LocalAuthentication
func configured() -> LAContext {
    let context = LAContext()
    context.localizedCancelTitle =
        String(localized: "Not now")
    context.localizedFallbackTitle = "" // hide fallback
    return context
}

إعادة استخدام مصادقة ناجحة

import LocalAuthentication
func reusableContext() -> LAContext {
    let context = LAContext()
    context.touchIDAuthenticationAllowableReuseDuration = 30
    return context
}

القياسات الحيوية مقابل تقييد Keychain

import LocalAuthentication
// A bare evaluatePolicy == true is bypassable if your
// logic is tampered with. Prefer SecAccessControl so
// the data is encrypted until auth succeeds.
let pairing = "combine LAContext with Keychain ACL"
_ = pairing

تدفق إلغاء قفل متكامل

import LocalAuthentication
func unlock() async -> Bool {
    let context = LAContext()
    var err: NSError?
    guard context.canEvaluatePolicy(
        .deviceOwnerAuthentication, error: &err) else {
        return false
    }
    return (try? await context.evaluatePolicy(
        .deviceOwnerAuthentication,
        localizedReason:
            String(localized: "Access your vault"))) ?? false
}

اختبار سريع

مراجعة