The first thing to notice is that this file defines an extension on the Item class. There are a number of important details and a few new concepts. to delete and recreate this implementation file for your updated model.Įxtension Item var createdAt: var done: var name: String? Choose "Create NSManagedObject Subclass…" from the Core Data editor menu Let's now take a look at the contents of Item+CoreDataProperties.swift. If you wish to add functionality to the class, you should add it here.
The comment Xcode has added to the class implementation is important.
#SWIFT DOWNCAST CODE#
Insert code here to add functionality to your managed object subclassĪs you can see, Xcode has created a class for us, Item, that inherits from NSManagedObject. The contents of Item.swift should be pretty easy to understand. I recommend using Xcode 7-preferably Xcode 7.1 or higher-to follow along. If you're using an earlier version of Xcode, then Xcode may have created only one file. Xcode should have create two files for you: Navigate to the files Xcode created for you and take a look at their contents. Don't forget to set Language to Swift and click Create to create the NSManagedObject subclass for the Item entity. But for Swift, it's best to check it as it makes your code more readable and less complex. When working with Objective-C, this option is an important consideration. Check the checkbox of the Item entity and click Next.Ĭhoose a location to store the class files of the NSManagedObject subclass and make sure that Use scalar properties for primitive data types is checked. In the next step, you are asked to select the entities for which you want to create an NSManagedObject subclass. Select New > File. from Xcode's File menu, choose the NSManagedObject subclass template from the Core Data section, and click Next.Ĭheck the checkbox of the correct data model, Done, from the list of data models and click Next. Open the data model of the project, Done.xcdatamodeld, and select the Item entity. While it's possible to manually create an NSManagedObject subclass for an entity, it's easier to let Xcode do the work for you.
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Download it from GitHub and open it in Xcode.Ĭreating an NSManagedObject subclass is very easy.
To save some time, we're going to revisit Done, the application we created earlier in this series. To make working with NSManagedObject instances easier, it's better to create an NSManagedObject subclass for each entity of the data model and that's what you'll learn in this article. Key value coding is great, but it is verbose and difficult to read if you're used to Swift's dot syntax. The above problem is easily solved by using string constants, but that's not the point I'm trying to make. In fact, every statement will result in an exception apart from the third statement, which uses the correct key as specified in the data model. tValue(NSDate(), forKey: "CREATEDAT")Įach statement in the above code snippet returns a different result. The following code snippet illustrates this problem well. Not only is the KVC syntax verbose, valueForKey(_:) and setValue(_:forKey:), it may also introduce errors that are the result of typos. This works fine, but from the moment your project has any kind of complexity, you'll quickly run into issues.
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In that project, we used key value coding (KVC) and key value observing (KVO) to create and update records. Earlier in this series, we created Done, a simple application to learn more about the NSFetchedResultsController class.
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