CODEWITHSUNDEEP
iosswiftswift2
Jake
Jake

Reputation: 26107

Check if AnyObject is empty or does not have a key or if value for that key is empty

In core data, I have an entity called "CachedRecipes" and in it an attribute called "jsonData".

I have a function to get JSON data from this attribute

func getJSONFromCoreData()->AnyObject    {

    var jsonDataInCoreData:AnyObject = ""

    do
    {
        let fetchRequest = NSFetchRequest(entityName: "CachedRecipes")

       let fetchedResults = try self.sharedContext.executeFetchRequest(fetchRequest)

        for (var i=0; i < fetchedResults.count; i++)
        {
            let single_result = fetchedResults[i]
            let out = single_result.valueForKey("jsonData")
            print(out)
            jsonDataInCoreData = out!
        }

    }
    catch
    {
        print("error")
    }

    return jsonDataInCoreData
}

I am using a statement in viewDidLoad of the same UIViewController to get the data like this:

let jsonDataFromCoreData = self.getJSONFromCoreData()

How can I check if jsonDataFromCoreData is empty or it doesn't have any key called jsonData and that key doesn't have any value? I need to print out an error if it happens.

Upvotes: 0

Views: 458

Answers (1)

Stefan Salatic
Stefan Salatic

Reputation: 4513

Change your function so it returns an optional

func getJSONFromCoreData()->AnyObject?    {

    var jsonDataInCoreData:AnyObject?

    do
    {
        let fetchRequest = NSFetchRequest(entityName: "CachedRecipes")

       let fetchedResults = try self.sharedContext.executeFetchRequest(fetchRequest)

        for (var i=0; i < fetchedResults.count; i++)
        {
            let single_result = fetchedResults[i]
            let out = single_result.valueForKey("jsonData")
            print(out)
            jsonDataInCoreData = out!
        }

    }
    catch
    {
        print("error")
    }

    return jsonDataInCoreData
}

And if it returns nil then it doesn't contain that data. You can just unwrap like this:

if let json = getJSONFromCoreData() {
    // Has some data
} else {
    // No data
}

Upvotes: 1

Related Questions