Touch and Face ID in SwiftUI

Code Block 
func authenticate() {
        let context = LAContext()
        var error: NSError?
        if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
            let reason = "We need to unlock your data."
                 context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { success, authenticationError in
                DispatchQueue.main.async {
                    if success {
                        self.isUnlocked = true
                    } else { 
                        userPressedCancel = false
                    }
                }
            }
        } else {
        }
    }