CODEWITHSUNDEEP
iosswiftvalidationcore-dataerror-handling
Maxi Mus
Maxi Mus

Reputation: 815

Error Domain Handling in Swift 2

I have the following code from a Swift 1.2 tutorial, which I can't manage to convert to Swift 2:

var val: AnyObject? = self.value
var error: NSError?
if !self.myManangedObject.validateValue(&val, forKey: self.key, error: &error) {
    var message: String!
    if error?.domain == "NSCocoaErrorDomain" {
        var userInfo:NSDictionary? = error?.userInfo
        var errorKey = userInfo?.valueForKey("NSValidationErrorKey") as String
        var reason = error?.localizedFailureReason
        message = NSLocalizedString("Validation error on \(errorKey)\rFailure Reason:\(reason)", comment: "Validation error on \(errorKey)\rFailure Reason: \(reason)")
    } else {
        message = error?.localizedDescription
    }
    // Create some alerts with the message
}

The self.value in the first line refers to the value for a CoreData attribute.

I understand I need to change the code to a do { try } catch { } construct. I am guessing line 3 would look something like this:

try self.myManagedObject.validateValue(&val, forKey: self.key)

However, this doesn't work as Xcode first suggests removing the pointer, and then says

"Cannot convert value of type 'AnyObject?' to expected argument type 'AutoreleasingUnsafeMutablePointer (...)"

Also, I am not sure how to handle the error?.domain statements. From searching the internet, the examples I found suggest handling the error types in an enumeration, but I don't see how that would apply here.

Btw, would it be possible to use the current version of Xcode to update this code from Swift 1.2 to 2.0?

Upvotes: 1

Views: 1457

Answers (1)

luk2302
luk2302

Reputation: 57114

The following is the minimal working example for what you are trying to do:

var mgc : NSManagedObjectContext!
var any : AnyObject?

do {
    let valid = try mgc.validateValue(&any, forKey: "myKey")
    // branch based on the valid
} catch let error as NSError {
    // here you go with your error handling
}

Can you take it from here?

Upvotes: 1

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