Integrate the FaceID or TouchID Authentication in iOS Apps

Dear Folks, today I am going to explain the proper way to integrate the Face ID or Touch ID in iOS App. Face ID and Touch ID are secure, familiar authentication methods that people trust. Follow below steps:

Step 1: Add NSFaceIDUsageDescription Key in info.plist file

<key>NSFaceIDUsageDescription</key>
<string>This app requires Face ID permission to authenticate using Face recognition.</string>

1 2	<key>NSFaceIDUsageDescription</key> <string>This app requires Face ID permission to authenticate using Face recognition.</string>

Step 2: Create a swift file with any name but it would be better to related to its functionality, Like BioMetrixFile.swift

Step 3: In BioMetrixFile write below codes and follow instructions. But before proceeding further import LocalAuthentication class in BioMetrixFile.

Now, create typealias for success or failure blocks to well manage Authentication Success or Failure.

public typealias AuthenticationSuccess = (() -> ())

public typealias AuthenticationFailure = ((AuthenticationError) -> ())

public typealias AuthenticationSuccess = (() -> ())

public typealias AuthenticationFailure = ((AuthenticationError) -> ())

Now written all string messages success or error, created enum for them.

let kBiometryNotAvailableReason = "BioMetrix authentication is not available for this device."

enum BioMetrixTouchIDErrors: String {
    //Touch ID
    case kTouchIdAuthenticationReason = "Confirm your fingerprint to authenticate."
    case kTouchIdPasscodeAuthenticationReason = "Touch ID is locked now, because of too many failed attempts. Enter passcode to unlock Touch ID."
    
    /// Error Messages Touch ID
    case kSetPasscodeToUseTouchID = "Please set device passcode to use Touch ID for authentication."
    case kNoFingerprintEnrolled = "There are no fingerprints enrolled in the device. Please go to Device Settings -> Touch ID & Passcode and enroll your fingerprints."
    case kDefaultTouchIDAuthenticationFailedReason = "Touch ID does not recognize your fingerprint. Please try again with your enrolled fingerprint."
    
}

enum BioMetrixFaceIDErrors: String{
    //Face ID
    case kFaceIdAuthenticationReason = "Confirm your face to authenticate."
    case kFaceIdPasscodeAuthenticationReason = "Face ID is locked now, because of too many failed attempts. Enter passcode to unlock Face ID."
    
    // Error Messages Face ID
    case kSetPasscodeToUseFaceID = "Please set device passcode to use Face ID for authentication."
    case kNoFaceIdentityEnrolled = "There is no face enrolled in the device. Please go to Device Settings -> Face ID & Passcode and enroll your face."
    case kDefaultFaceIDAuthenticationFailedReason = "Face ID does not recognize your face. Please try again with your enrolled face."
}

let kBiometryNotAvailableReason = "BioMetrix authentication is not available for this device."

enum BioMetrixTouchIDErrors: String {

//Touch ID

case kTouchIdAuthenticationReason = "Confirm your fingerprint to authenticate."

case kTouchIdPasscodeAuthenticationReason = "Touch ID is locked now, because of too many failed attempts. Enter passcode to unlock Touch ID."

/// Error Messages Touch ID

case kSetPasscodeToUseTouchID = "Please set device passcode to use Touch ID for authentication."

case kNoFingerprintEnrolled = "There are no fingerprints enrolled in the device. Please go to Device Settings -> Touch ID & Passcode and enroll your fingerprints."

case kDefaultTouchIDAuthenticationFailedReason = "Touch ID does not recognize your fingerprint. Please try again with your enrolled fingerprint."

}

enum BioMetrixFaceIDErrors: String{

//Face ID

case kFaceIdAuthenticationReason = "Confirm your face to authenticate."

case kFaceIdPasscodeAuthenticationReason = "Face ID is locked now, because of too many failed attempts. Enter passcode to unlock Face ID."

// Error Messages Face ID

case kSetPasscodeToUseFaceID = "Please set device passcode to use Face ID for authentication."

case kNoFaceIdentityEnrolled = "There is no face enrolled in the device. Please go to Device Settings -> Face ID & Passcode and enroll your face."

case kDefaultFaceIDAuthenticationFailedReason = "Face ID does not recognize your face. Please try again with your enrolled face."

}

Step 4: Created a Singleton class with name BioMetrixAuthentication which is subclass of NSObject.

open class BioMetrixAuthentication: NSObject {
    public static let shared = BioMetrixAuthentication()
}

open class BioMetrixAuthentication: NSObject {

public static let shared = BioMetrixAuthentication()

}

Step 5: Added a class function to check whether device has TouchID available or not.

    class func canAuthenticate() -> Bool {
        
        var isBioMetrixAuthenticationAvailable = false
        var error: NSError? = nil
        
        if LAContext().canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error) {
            isBioMetrixAuthenticationAvailable = (error == nil)
        }
        return isBioMetrixAuthenticationAvailable
    }

class func canAuthenticate() -> Bool {

var isBioMetrixAuthenticationAvailable = false

var error: NSError? = nil

if LAContext().canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error) {

isBioMetrixAuthenticationAvailable = (error == nil)

}

return isBioMetrixAuthenticationAvailable

}

Step 6: Added a function to Check BioMetrix Authentication (FaceId / Touch Id)

    class func authenticateWithBioMetrixs(reason: String, fallbackTitle: String? = "", cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {
        let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultBioMetrixAuthenticationReason() : reason
        
        let context = LAContext()
        context.localizedFallbackTitle = fallbackTitle
        
        // cancel button title
        if #available(iOS 10.0, *) {
            context.localizedCancelTitle = cancelTitle
        }
        
        // authenticate
        BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)
    }

class func authenticateWithBioMetrixs(reason: String, fallbackTitle: String? = "", cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {

let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultBioMetrixAuthenticationReason() : reason

let context = LAContext()

context.localizedFallbackTitle = fallbackTitle

// cancel button title

if #available(iOS 10.0, *) {

context.localizedCancelTitle = cancelTitle

}

// authenticate

BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)

}

Step 7: Add a function to check device passcode if user fails to authenticate himself using touchID or faceID several times.

/// Check for device passcode authentication
    class func authenticateWithPasscode(reason: String, cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {
        let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultPasscodeAuthenticationReason() : reason
        
        let context = LAContext()
        
        // cancel button title
        if #available(iOS 10.0, *) {
            context.localizedCancelTitle = cancelTitle
        }
        
        // authenticate
        if #available(iOS 9.0, *) {
            BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthentication, with: context, reason: reasonString, success: successBlock, failure: failureBlock)
        } else {
            // Fallback on earlier versions
            BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)
        }
    }

/// Check for device passcode authentication

class func authenticateWithPasscode(reason: String, cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {

let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultPasscodeAuthenticationReason() : reason

let context = LAContext()

// cancel button title

if #available(iOS 10.0, *) {

context.localizedCancelTitle = cancelTitle

}

// authenticate

if #available(iOS 9.0, *) {

BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthentication, with: context, reason: reasonString, success: successBlock, failure: failureBlock)

} else {

// Fallback on earlier versions

BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)

}

Step 8: Add a method to check if device supports faceID or not.

public func faceIDAvailable() -> Bool {
        if #available(iOS 11.0, *) {
            let context = LAContext()
            return (context.canEvaluatePolicy(LAPolicy.deviceOwnerAuthentication, error: nil) && context.biometryType == .faceID)
        }
        return false
    }

public func faceIDAvailable() -> Bool {

if #available(iOS 11.0, *) {

let context = LAContext()

return (context.canEvaluatePolicy(LAPolicy.deviceOwnerAuthentication, error: nil) && context.biometryType == .faceID)

}

return false

}

Step 9: Add a method to show authentication message regarding faceID or TouchId. If device supports faceID, it will pick the value from BioMetrixFaceIDError Enum otherwise from BioMetrixTouchIDErrors Enum.

func defaultBioMetrixAuthenticationReason() -> String {
        return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdAuthenticationReason.rawValue
    }

func defaultBioMetrixAuthenticationReason() -> String {

return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdAuthenticationReason.rawValue

}

Step 10. Now Add a method to handle the error message, when user has too many failed attempts for faceID or TouchId.

 func defaultPasscodeAuthenticationReason() -> String {
        return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue
    }

func defaultPasscodeAuthenticationReason() -> String {

return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue

}

Step 11. Now Add method to evaluate the specified policy for faceID or TouchID. More info: https://developer.apple.com/documentation/localauthentication/lacontext

func evaluate(policy: LAPolicy, with context: LAContext, reason: String, success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {
        
        context.evaluatePolicy(policy, localizedReason: reason) { (success, err) in
            DispatchQueue.main.async {
                if success { successBlock() }
                else {
                    let errorType = AuthenticationError.initWithError(err as! LAError)
                    failureBlock(errorType)
                }
            }
        }
    }

func evaluate(policy: LAPolicy, with context: LAContext, reason: String, success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {

context.evaluatePolicy(policy, localizedReason: reason) { (success, err) in

DispatchQueue.main.async {

if success { successBlock() }

else {

let errorType = AuthenticationError.initWithError(err as! LAError)

failureBlock(errorType)

}

Step 12: Add AuthenticationError enum to manage errors.

public enum AuthenticationError {
    
    case failed, canceledByUser, fallback, canceledBySystem, passcodeNotSet, biometryNotAvailable, biometryNotEnrolled, biometryLockedout, other
    
    public static func initWithError(_ error: LAError) -> AuthenticationError {
        switch Int32(error.errorCode) {
            
        case kLAErrorAuthenticationFailed:
            return failed
        case kLAErrorUserCancel:
            return canceledByUser
        case kLAErrorUserFallback:
            return fallback
        case kLAErrorSystemCancel:
            return canceledBySystem
        case kLAErrorPasscodeNotSet:
            return passcodeNotSet
        case kLAErrorBiometryNotAvailable:
            return biometryNotAvailable
        case kLAErrorBiometryNotEnrolled:
            return biometryNotEnrolled
        case kLAErrorBiometryLockout:
            return biometryLockedout
        default:
            return other
        }
    }
    
    // get error message based on type
    public func message() -> String {
        let authentication = BioMetrixAuthentication.shared
        
        switch self {
        case .canceledByUser, .fallback, .canceledBySystem:
            return ""
        case .passcodeNotSet:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kSetPasscodeToUseFaceID.rawValue : BioMetrixTouchIDErrors.kSetPasscodeToUseTouchID.rawValue
        case .biometryNotAvailable:
            return kBiometryNotAvailableReason
        case .biometryNotEnrolled:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kNoFaceIdentityEnrolled.rawValue : BioMetrixTouchIDErrors.kNoFingerprintEnrolled.rawValue
        case .biometryLockedout:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue
        default:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kDefaultFaceIDAuthenticationFailedReason.rawValue : BioMetrixTouchIDErrors.kDefaultTouchIDAuthenticationFailedReason.rawValue
        }
    }
}

public enum AuthenticationError {

case failed, canceledByUser, fallback, canceledBySystem, passcodeNotSet, biometryNotAvailable, biometryNotEnrolled, biometryLockedout, other

public static func initWithError(_ error: LAError) -> AuthenticationError {

switch Int32(error.errorCode) {

case kLAErrorAuthenticationFailed:

return failed

case kLAErrorUserCancel:

return canceledByUser

case kLAErrorUserFallback:

return fallback

case kLAErrorSystemCancel:

return canceledBySystem

case kLAErrorPasscodeNotSet:

return passcodeNotSet

case kLAErrorBiometryNotAvailable:

return biometryNotAvailable

case kLAErrorBiometryNotEnrolled:

return biometryNotEnrolled

case kLAErrorBiometryLockout:

return biometryLockedout

default:

return other

}

// get error message based on type

public func message() -> String {

let authentication = BioMetrixAuthentication.shared

switch self {

case .canceledByUser, .fallback, .canceledBySystem:

return ""

case .passcodeNotSet:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kSetPasscodeToUseFaceID.rawValue : BioMetrixTouchIDErrors.kSetPasscodeToUseTouchID.rawValue

case .biometryNotAvailable:

return kBiometryNotAvailableReason

case .biometryNotEnrolled:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kNoFaceIdentityEnrolled.rawValue : BioMetrixTouchIDErrors.kNoFingerprintEnrolled.rawValue

case .biometryLockedout:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue

default:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kDefaultFaceIDAuthenticationFailedReason.rawValue : BioMetrixTouchIDErrors.kDefaultTouchIDAuthenticationFailedReason.rawValue

}

If you followed all the steps mentioned above, your BioMetrixFile.swift will look like this.

import UIKit
import LocalAuthentication

public typealias AuthenticationSuccess = (() -> ())

public typealias AuthenticationFailure = ((AuthenticationError) -> ())

let kBiometryNotAvailableReason = "BioMetrix authentication is not available for this device."

enum BioMetrixTouchIDErrors: String {
    //Touch ID
    case kTouchIdAuthenticationReason = "Confirm your fingerprint to authenticate."
    case kTouchIdPasscodeAuthenticationReason = "Touch ID is locked now, because of too many failed attempts. Enter passcode to unlock Touch ID."
    
    /// Error Messages Touch ID
    case kSetPasscodeToUseTouchID = "Please set device passcode to use Touch ID for authentication."
    case kNoFingerprintEnrolled = "There are no fingerprints enrolled in the device. Please go to Device Settings -> Touch ID & Passcode and enroll your fingerprints."
    case kDefaultTouchIDAuthenticationFailedReason = "Touch ID does not recognize your fingerprint. Please try again with your enrolled fingerprint."
    
}

enum BioMetrixFaceIDErrors: String{
    //Face ID
    case kFaceIdAuthenticationReason = "Confirm your face to authenticate."
    case kFaceIdPasscodeAuthenticationReason = "Face ID is locked now, because of too many failed attempts. Enter passcode to unlock Face ID."
    
    // Error Messages Face ID
    case kSetPasscodeToUseFaceID = "Please set device passcode to use Face ID for authentication."
    case kNoFaceIdentityEnrolled = "There is no face enrolled in the device. Please go to Device Settings -> Face ID & Passcode and enroll your face."
    case kDefaultFaceIDAuthenticationFailedReason = "Face ID does not recognize your face. Please try again with your enrolled face."
}




open class BioMetrixAuthentication: NSObject {
    // MARK: - Singleton
    public static let shared = BioMetrixAuthentication()
}

// MARK:- Public
public extension BioMetrixAuthentication {
    
    /// checks if TouchID or FaceID is available on the device.
    class func canAuthenticate() -> Bool {
        
        var isBioMetrixAuthenticationAvailable = false
        var error: NSError? = nil
        
        if LAContext().canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error) {
            isBioMetrixAuthenticationAvailable = (error == nil)
        }
        return isBioMetrixAuthenticationAvailable
    }
    
    /// Check for BioMetrix authentication
    class func authenticateWithBioMetrixs(reason: String, fallbackTitle: String? = "", cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {
        let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultBioMetrixAuthenticationReason() : reason
        
        let context = LAContext()
        context.localizedFallbackTitle = fallbackTitle
        
        // cancel button title
        if #available(iOS 10.0, *) {
            context.localizedCancelTitle = cancelTitle
        }
        
        // authenticate
        BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)
    }
    
    /// Check for device passcode authentication
    class func authenticateWithPasscode(reason: String, cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {
        let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultPasscodeAuthenticationReason() : reason
        
        let context = LAContext()
        
        // cancel button title
        if #available(iOS 10.0, *) {
            context.localizedCancelTitle = cancelTitle
        }
        
        // authenticate
        if #available(iOS 9.0, *) {
            BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthentication, with: context, reason: reasonString, success: successBlock, failure: failureBlock)
        } else {
            // Fallback on earlier versions
            BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)
        }
    }
    
    /// checks if face id is avaiable on device
    public func faceIDAvailable() -> Bool {
        if #available(iOS 11.0, *) {
            let context = LAContext()
            return (context.canEvaluatePolicy(LAPolicy.deviceOwnerAuthentication, error: nil) && context.biometryType == .faceID)
        }
        return false
    }
}

// MARK:- Private
extension BioMetrixAuthentication {
    
    /// get authentication reason to show while authentication
    func defaultBioMetrixAuthenticationReason() -> String {
        return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdAuthenticationReason.rawValue
    }
    
    /// get passcode authentication reason to show while entering device passcode after multiple failed attempts.
    func defaultPasscodeAuthenticationReason() -> String {
        return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue
    }
    
    /// evaluate policy
    func evaluate(policy: LAPolicy, with context: LAContext, reason: String, success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {
        
        context.evaluatePolicy(policy, localizedReason: reason) { (success, err) in
            DispatchQueue.main.async {
                if success { successBlock() }
                else {
                    let errorType = AuthenticationError.initWithError(err as! LAError)
                    failureBlock(errorType)
                }
            }
        }
    }
}


//----- Validations Errors // Success  ------
public enum AuthenticationError {
    
    case failed, canceledByUser, fallback, canceledBySystem, passcodeNotSet, biometryNotAvailable, biometryNotEnrolled, biometryLockedout, other
    
    public static func initWithError(_ error: LAError) -> AuthenticationError {
        switch Int32(error.errorCode) {
            
        case kLAErrorAuthenticationFailed:
            return failed
        case kLAErrorUserCancel:
            return canceledByUser
        case kLAErrorUserFallback:
            return fallback
        case kLAErrorSystemCancel:
            return canceledBySystem
        case kLAErrorPasscodeNotSet:
            return passcodeNotSet
        case kLAErrorBiometryNotAvailable:
            return biometryNotAvailable
        case kLAErrorBiometryNotEnrolled:
            return biometryNotEnrolled
        case kLAErrorBiometryLockout:
            return biometryLockedout
        default:
            return other
        }
    }
    
    // get error message based on type
    public func message() -> String {
        let authentication = BioMetrixAuthentication.shared
        
        switch self {
        case .canceledByUser, .fallback, .canceledBySystem:
            return ""
        case .passcodeNotSet:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kSetPasscodeToUseFaceID.rawValue : BioMetrixTouchIDErrors.kSetPasscodeToUseTouchID.rawValue
        case .biometryNotAvailable:
            return kBiometryNotAvailableReason
        case .biometryNotEnrolled:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kNoFaceIdentityEnrolled.rawValue : BioMetrixTouchIDErrors.kNoFingerprintEnrolled.rawValue
        case .biometryLockedout:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue
        default:
            return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kDefaultFaceIDAuthenticationFailedReason.rawValue : BioMetrixTouchIDErrors.kDefaultTouchIDAuthenticationFailedReason.rawValue
        }
    }
}

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import UIKit

import LocalAuthentication

public typealias AuthenticationSuccess = (() -> ())

public typealias AuthenticationFailure = ((AuthenticationError) -> ())

let kBiometryNotAvailableReason = "BioMetrix authentication is not available for this device."

enum BioMetrixTouchIDErrors: String {

//Touch ID

case kTouchIdAuthenticationReason = "Confirm your fingerprint to authenticate."

case kTouchIdPasscodeAuthenticationReason = "Touch ID is locked now, because of too many failed attempts. Enter passcode to unlock Touch ID."

/// Error Messages Touch ID

case kSetPasscodeToUseTouchID = "Please set device passcode to use Touch ID for authentication."

case kNoFingerprintEnrolled = "There are no fingerprints enrolled in the device. Please go to Device Settings -> Touch ID & Passcode and enroll your fingerprints."

case kDefaultTouchIDAuthenticationFailedReason = "Touch ID does not recognize your fingerprint. Please try again with your enrolled fingerprint."

}

enum BioMetrixFaceIDErrors: String{

//Face ID

case kFaceIdAuthenticationReason = "Confirm your face to authenticate."

case kFaceIdPasscodeAuthenticationReason = "Face ID is locked now, because of too many failed attempts. Enter passcode to unlock Face ID."

// Error Messages Face ID

case kSetPasscodeToUseFaceID = "Please set device passcode to use Face ID for authentication."

case kNoFaceIdentityEnrolled = "There is no face enrolled in the device. Please go to Device Settings -> Face ID & Passcode and enroll your face."

case kDefaultFaceIDAuthenticationFailedReason = "Face ID does not recognize your face. Please try again with your enrolled face."

}

open class BioMetrixAuthentication: NSObject {

// MARK: - Singleton

public static let shared = BioMetrixAuthentication()

}

// MARK:- Public

public extension BioMetrixAuthentication {

/// checks if TouchID or FaceID is available on the device.

class func canAuthenticate() -> Bool {

var isBioMetrixAuthenticationAvailable = false

var error: NSError? = nil

if LAContext().canEvaluatePolicy(LAPolicy.deviceOwnerAuthenticationWithBiometrics, error: &error) {

isBioMetrixAuthenticationAvailable = (error == nil)

}

return isBioMetrixAuthenticationAvailable

}

/// Check for BioMetrix authentication

let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultBioMetrixAuthenticationReason() : reason

let context = LAContext()

context.localizedFallbackTitle = fallbackTitle

// cancel button title

if #available(iOS 10.0, *) {

context.localizedCancelTitle = cancelTitle

}

// authenticate

BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)

}

/// Check for device passcode authentication

class func authenticateWithPasscode(reason: String, cancelTitle: String? = "", success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {

let reasonString = reason.isEmpty ? BioMetrixAuthentication.shared.defaultPasscodeAuthenticationReason() : reason

let context = LAContext()

// cancel button title

if #available(iOS 10.0, *) {

context.localizedCancelTitle = cancelTitle

}

// authenticate

if #available(iOS 9.0, *) {

BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthentication, with: context, reason: reasonString, success: successBlock, failure: failureBlock)

} else {

// Fallback on earlier versions

BioMetrixAuthentication.shared.evaluate(policy: LAPolicy.deviceOwnerAuthenticationWithBiometrics, with: context, reason: reasonString, success: successBlock, failure: failureBlock)

}

/// checks if face id is avaiable on device

public func faceIDAvailable() -> Bool {

if #available(iOS 11.0, *) {

let context = LAContext()

return (context.canEvaluatePolicy(LAPolicy.deviceOwnerAuthentication, error: nil) && context.biometryType == .faceID)

}

return false

}

// MARK:- Private

extension BioMetrixAuthentication {

/// get authentication reason to show while authentication

func defaultBioMetrixAuthenticationReason() -> String {

return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdAuthenticationReason.rawValue

}

/// get passcode authentication reason to show while entering device passcode after multiple failed attempts.

func defaultPasscodeAuthenticationReason() -> String {

return faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue

}

/// evaluate policy

func evaluate(policy: LAPolicy, with context: LAContext, reason: String, success successBlock:@escaping AuthenticationSuccess, failure failureBlock:@escaping AuthenticationFailure) {

context.evaluatePolicy(policy, localizedReason: reason) { (success, err) in

DispatchQueue.main.async {

if success { successBlock() }

else {

let errorType = AuthenticationError.initWithError(err as! LAError)

failureBlock(errorType)

}

//----- Validations Errors // Success ------

public enum AuthenticationError {

case failed, canceledByUser, fallback, canceledBySystem, passcodeNotSet, biometryNotAvailable, biometryNotEnrolled, biometryLockedout, other

public static func initWithError(_ error: LAError) -> AuthenticationError {

switch Int32(error.errorCode) {

case kLAErrorAuthenticationFailed:

return failed

case kLAErrorUserCancel:

return canceledByUser

case kLAErrorUserFallback:

return fallback

case kLAErrorSystemCancel:

return canceledBySystem

case kLAErrorPasscodeNotSet:

return passcodeNotSet

case kLAErrorBiometryNotAvailable:

return biometryNotAvailable

case kLAErrorBiometryNotEnrolled:

return biometryNotEnrolled

case kLAErrorBiometryLockout:

return biometryLockedout

default:

return other

}

// get error message based on type

public func message() -> String {

let authentication = BioMetrixAuthentication.shared

switch self {

case .canceledByUser, .fallback, .canceledBySystem:

return ""

case .passcodeNotSet:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kSetPasscodeToUseFaceID.rawValue : BioMetrixTouchIDErrors.kSetPasscodeToUseTouchID.rawValue

case .biometryNotAvailable:

return kBiometryNotAvailableReason

case .biometryNotEnrolled:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kNoFaceIdentityEnrolled.rawValue : BioMetrixTouchIDErrors.kNoFingerprintEnrolled.rawValue

case .biometryLockedout:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kFaceIdPasscodeAuthenticationReason.rawValue : BioMetrixTouchIDErrors.kTouchIdPasscodeAuthenticationReason.rawValue

default:

return authentication.faceIDAvailable() ? BioMetrixFaceIDErrors.kDefaultFaceIDAuthenticationFailedReason.rawValue : BioMetrixTouchIDErrors.kDefaultTouchIDAuthenticationFailedReason.rawValue

}

Now moving to the UIViewController, where you want to integrate the FaceID or TouchID. Create UIButton IBAction method and follow below proper steps to manage the correct flow of authentication. Adding below lines of code in IBAction method of this button.

Steps 13: Starting Authentication by calling the class function of BioMetrixAuthentication Class in BioMetrixFile.swift file.

        // start authentication
        BioMetrixAuthentication.authenticateWithBioMetrixs(reason: "", success: {
            
            // authentication successful
            self.showLoginSucessAlert()
            
        }, failure: { [weak self] (error) in
            
            // do nothing on canceled
            if error == .canceledByUser || error == .canceledBySystem {
                return
            }

                // device does not support biometric (face id or touch id) authentication
            else if error == .biometryNotAvailable {
                print("Show Error: ", error.message())
            }

                // show alternatives on fallback button clicked
            else if error == .fallback {
                // here we're entering username and password
                print("Normal login with username & password, make textfield first responder")
            }
                
                // No biometry enrolled in this device, ask user to register fingerprint or face
            else if error == .biometryNotEnrolled {
                self?.showGotoSettingsAlert(message: error.message())
            }
                
                // Biometry is locked out now, because there were too many failed attempts.
                // Need to enter device passcode to unlock.
            else if error == .biometryLockedout {
                self?.showPasscodeAuthentication(message: error.message())
            }
                
                // show error on authentication failed
            else {
                print("Show Error: ", error.message())
            }
        })

// start authentication

BioMetrixAuthentication.authenticateWithBioMetrixs(reason: "", success: {

// authentication successful

self.showLoginSucessAlert()

}, failure: { [weak self] (error) in

// do nothing on canceled

if error == .canceledByUser || error == .canceledBySystem {

return

}

// device does not support biometric (face id or touch id) authentication

else if error == .biometryNotAvailable {

print("Show Error: ", error.message())

}

// show alternatives on fallback button clicked

else if error == .fallback {

// here we're entering username and password

print("Normal login with username & password, make textfield first responder")

}

// No biometry enrolled in this device, ask user to register fingerprint or face

else if error == .biometryNotEnrolled {

self?.showGotoSettingsAlert(message: error.message())

}

// Biometry is locked out now, because there were too many failed attempts.

// Need to enter device passcode to unlock.

else if error == .biometryLockedout {

self?.showPasscodeAuthentication(message: error.message())

}

// show error on authentication failed

else {

print("Show Error: ", error.message())

}

})

Step 14: Add method to show passcode authentication

 // show passcode authentication
    func showPasscodeAuthentication(message: String) {
        
        BioMetrixAuthentication.authenticateWithPasscode(reason: message, success: {
            // passcode authentication success
            self.showLoginSucessAlert()
            
        }) { (error) in
            print("Show Error: ", error.message())
        }
    }

// show passcode authentication

func showPasscodeAuthentication(message: String) {

BioMetrixAuthentication.authenticateWithPasscode(reason: message, success: {

// passcode authentication success

self.showLoginSucessAlert()

}) { (error) in

print("Show Error: ", error.message())

}

Step 15: Adding a common method for login success.

func showLoginSucessAlert(){
        print("Login Success")
    }

func showLoginSucessAlert(){

print("Login Success")

}

Step 16: Handling the situation, when user has not enabled FaceId or TouchId.

    func showGotoSettingsAlert(message: String){
        let alert = UIAlertController(title: "Go to settings", message: message, preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (self) in
            let url = URL(string: "App-Prefs:root=TOUCHID_PASSCODE")
            if UIApplication.shared.canOpenURL(url!) {
                UIApplication.shared.open(url!, options: [:], completionHandler: nil)
            }
        }))
        
        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
        
        self.present(alert, animated: true)
    }

func showGotoSettingsAlert(message: String){

let alert = UIAlertController(title: "Go to settings", message: message, preferredStyle: .alert)

alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (self) in

let url = URL(string: "App-Prefs:root=TOUCHID_PASSCODE")

if UIApplication.shared.canOpenURL(url!) {

UIApplication.shared.open(url!, options: [:], completionHandler: nil)

}

}))

alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))

self.present(alert, animated: true)

}

I would love to hear from you, if you have any doubt regarding code please leave comment below.

Rakesh Sharma 28 September 2018

. . .

Integrate the FaceID or TouchID Authentication in iOS Apps

If you followed all the steps mentioned above, your BioMetrixFile.swift will look like this.

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