"switch(error!.code)" in canEvaluatePolicy function does not exist in Swift 3 (Xcode 8)

Question

I'm converting below code to Swift 3.

 if context.canEvaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, error:nil) {

  // 2.
  context.evaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics,
    localizedReason: "Logging in with Touch ID",
    reply: { (success : Bool, error : NSError? ) -> Void in

      // 3.
      dispatch_async(dispatch_get_main_queue(), {
        if success {
          self.performSegueWithIdentifier("dismissLogin", sender: self)
        }

        if error != nil {

          var message : NSString
          var showAlert : Bool

          // 4.
          switch(error!.code) {

Step 4 does not work anymore on Xcode 8, Swift 3. So I could not do the following cases:

switch(error!.code) {
          case LAError.AuthenticationFailed.rawValue:
            message = "There was a problem verifying your identity."
            showAlert = true
            break;

Currently, it's seems there was no solution that I could find yet. Any suggestion, please let me know.

Thanks a lot!

No solution yet? The first hit for `[swift3] error code` is http://stackoverflow.com/questions/38711269/accessing-code-in-swift-3-error. — Martin R, Sep 28 '16 at 09:52

Nirav D · Accepted Answer · 2016-09-28T09:56:25.173

9

First change your reply closure of evaluatePolicy method, in Swift 3 it is Error not NSError.

reply: { (success : Bool, error : Error? ) -> Void in

Second, change performSegue with identifier like this.

performSegue(withIdentifier: "dismissLogin", sender: self)

In Swift 3 you need to convert Error object to NSError or use _code with Error instance instead of code.

switch((error! as NSError).code)

OR

switch(error!._code)

You need to also change you dispatch syntax like this.

Dispatch.async.main {
    //write code
}

edited Sep 28 '16 at 09:56

answered Sep 28 '16 at 09:39

Nirav D

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The first option is working a charm, bro. You're the best. Thanks a lot! – Va Visal Sep 28 '16 at 10:07
Welcome mate :) – Nirav D Sep 28 '16 at 10:10
1

He should also use `if let error = error` instead of `if error != nil` and avoid force unwrap the error object. – bsarr007 Sep 28 '16 at 10:15

score 2 · Answer 2 · answered Oct 03 '16 at 14:37

This actually got a lot easier

context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: "Logging in with Touch ID", reply: { (success : Bool, error : Error? ) -> Void in

  // 3.
  DispatchQueue.main.async {
    if success {
      self.performSegueWithIdentifier("dismissLogin", sender: self)
    }

    if let error = error {

      var message : NSString
      var showAlert : Bool

      // 4.
      switch error {
          case LAError.userCancel:
              //do stuff

This is mostly from memory, but I think it is correct.

"switch(error!.code)" in canEvaluatePolicy function does not exist in Swift 3 (Xcode 8)

2 Answers2