iOS fingerprint unlock verification TouchID function

#import <LocalAuthentication/>

//The fingerprint recognition interface is only supported after iOS 8.0  if ([UIDevice currentDevice]. < 8.0) {
    return;
  }

- (void)evaluateAuthenticate
{
  //Create LAContext  LAContext* context = [[LAContext alloc] init];
  NSError* error = nil;
  NSString* result = @"Please verify that you have fingerprints";
  //First use canEvaluatePolicy to determine the device support status  if ([context canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&error]) {
    //Support fingerprint verification    [context evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:result reply:^(BOOL success, NSError *error) {
      if (success) {
        //The verification is successful, the main thread handles the UI      }
      else
      {
        NSLog(@"%@",);
        switch () {
          case LAErrorSystemCancel:
          {
            //The system cancels the authorization, such as other APPs entering            break;
          }
          case LAErrorUserCancel:
          {
            //User unverified Touch ID            break;
          }
          case LAErrorAuthenticationFailed:
          {
            //Authorization failed            break;
          }
          case LAErrorPasscodeNotSet:
          {
            //The system does not set a password            break;
          }
          case LAErrorTouchIDNotAvailable:
          {
            //The device Touch ID is not available, for example not opened            break;
          }
          case LAErrorTouchIDNotEnrolled:
          {
            //The device Touch ID is not available and the user has not entered it            break;
          }
          case LAErrorUserFallback:
          {
            [[NSOperationQueue mainQueue] addOperationWithBlock:^{
              //The user selects to enter the password and switches to the main thread processing            }];
            break;
          }
          default:
          {
            [[NSOperationQueue mainQueue] addOperationWithBlock:^{
              //Other situations, switch main thread processing            }];
            break;
          }
        }
      }
    }];
  }
  else
  {
    //No fingerprint recognition is supported, LOG error details    NSLog(@"Fingerprint recognition is not supported");
    switch () {
      case LAErrorTouchIDNotEnrolled:
      {
        NSLog(@"TouchID is not enrolled");
        break;
      }
      case LAErrorPasscodeNotSet:
      {
        NSLog(@"A passcode has not been set");
        break;
      }
      default:
      {
        NSLog(@"TouchID not available");
        break;
      }
    }
    NSLog(@"%@",);
  }
}