Hi Charles,
I do believe you :)
The problem is that this doesn't work without a compiler warning if you switch
over every case except for the deprecated ones because then the compiler warns
that "default will never be executed".
As per my first mail feel free to try this out in a playground:
private func handleLocalAuthenticationError(_ error: LAError) {
switch error.code {
case .userCancel, .appCancel, .systemCancel:
// Handle cancelation
case .authenticationFailed:
// Handle failure
case .passcodeNotSet:
// Handle passcode absence
case .biometryNotEnrolled:
// Handle no biometry enrollment
case .biometryNotAvailable:
// Handle no biometry availabe
case .biometryLockout:
// Handle biometry Lockout
case .userFallback:
// Handle user fallback
case .invalidContext:
// Handle failure with invalid context
case .notInteractive:
// Handle no interaction allowed error
default: // <- Here the compiler emits
a warning that the default will never be executed.
// hopefully only deprecated cases
break
}
}
- Dennis
> On Nov 5, 2017, at 4:13 PM, Charles Srstka <cocoa...@charlessoft.com> wrote:
>
>> On Nov 5, 2017, at 3:14 AM, Dennis Weissmann <den...@dennisweissmann.me>
>> wrote:
>>
>> Hi Charles,
>>
>> You are right (the `default` case would not catch the deprecated values but
>> only new ones introduced in future releases), but the compiler doesn’t seem
>> to know that :(
>>
>> But now that you say it, one approach could be to pattern match the raw
>> values (and, well, have a default clause, which I really want to avoid) 🤔
>>
>> - Dennis
>>
>> Sent from my iPhone
>
> Hi Dennis,
>
> What I am saying is that the new cases have the same raw values as the old
> ones. touchIDNotAvailable is -6; biometryNotAvailable is -6.
> touchIDNotEnrolled is -7; biometryNotEnrolled is -7. touchIDLockout it -8;
> biometryLockout is -8. They’re just aliases to each other, so if you handle
> one, you don’t have to handle the other. You can literally ignore the
> deprecated values and treat them as if they don’t exist. Try this code for
> yourself if you don’t believe me:
>
> let err = LAError.touchIDLockout
>
> switch err {
> case LAError.biometryLockout:
> print("biometry lockout")
> default:
> print("default")
> }
>
> This prints “biometry lockout”.
>
> Charles
>
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