Swift 2 Type casting Dictionaries

Question

I have this code in Swift 1.2:

self.publicDatabase!.performQuery(query, inZoneWithID: nil) {
            results, error in
            if error != nil {
                NotificationUtility.postNotification(Notify.CloudKitVenuesRetrieveFailed, userinfo: ["result":results, "error":error])
            }
            else
            {
                NotificationUtility.postNotification(Notify.CloudKitVenuesRetrieveSuccess, userinfo: ["result":results])
            }
        }

But in Swift 2.0 this yields several compiler errors:

"Type of expression is ambiguous without more context"

and

"Cannot convert value of type '[String : [CKRecord]?]' to expected argument type '[NSObject : AnyObject]?'"

I know how to fix it to make the error go away, but it seems very ugly and hacky:

self.publicDatabase!.performQuery(query, inZoneWithID: nil) {
            results, error in
            if error != nil {
                NotificationUtility.postNotification(Notify.CloudKitVenuesRetrieveFailed, userinfo: ["result":results as! AnyObject, "error":error as! AnyObject])
            }
            else
            {
                NotificationUtility.postNotification(Notify.CloudKitVenuesRetrieveSuccess, userinfo: ["result":results as! AnyObject])
            }
        }

Is there a better way than having to go through every item in the dictionary and force downcast it to "AnyObject"?

Scott Austin Scott Austin · Accepted Answer · 2015-09-18T13:16:59

You never want to cast down to AnyObject. My guess here is that your fix works because you're unwrapping an optional, not because you're casting to AnyObject. I'm guessing, because I don't know what type results and error actually are, but this will likely work:

self.publicDatabase!.performQuery(query, inZoneWithID: nil) {
        results, error in
        if error != nil {
            NotificationUtility.postNotification(Notify.CloudKitVenuesRetrieveFailed, userinfo: ["result":results!, "error":error!])
        }
        else
        {
            NotificationUtility.postNotification(Notify.CloudKitVenuesRetrieveSuccess, userinfo: ["result":results!])
        }
    }

Swift 2 Type casting Dictionaries

1 Answers