JACoreData is a simple wrapper for Core Data objects in swift iOS projects. While fairly lightweight, this library makes fetching, creating, and saving NSManagedObjects easier and cleaner. Simply conform your already laid out NSManagedObject files to the ManagedObjectType protocol in JACoreData and you instantly gain access to multiple convenience methods.

Installation

JACoreData is designed to be installed using Carthage.

Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.

You can install Carthage with Homebrew using the following command:

$ brew update
$ brew install carthage

To integrate JACoreData into your Xcode project using Carthage, specify it in your Cartfile:

github "jakt/JACoreData.git"

Run carthage to build the framework and drag the built JACoreData.framework into your Xcode project.

Requirements

JACoreData Version	Minimum iOS Target
0.x	iOS 9
1.x	iOS 8

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Usage

Creating ManagedObjectTypes

The ManagedObjectType protocol can be applied to any NSManagedObject and simply requires the setting of the entityName variable. You can also optionally implement the defaultSortDescriptors variable for easier use with an NSFetchedResultsController.

extension User: ManagedObjectType {
    public static var entityName: String {
        return "User"
    }
    
    public static var defaultSortDescriptors: [NSSortDescriptor] {
        return []
    }
}

Fetching Objects

To fetch a single NSManagedObject object that conforms to the ManagedObjectType protocol, use findOrFetchInContext(moc: NSManagedObjectContext, matchingPredicate predicate: NSPredicate) -> Self?. This will return nil if no object in the database matches the given predicate.

To fetch more than one object, use fetchInContext(context: NSManagedObjectContext, configurationBlock: NSFetchRequest -> () = { _ in }) -> [Self].

Inserting a Managed Object

Inserting into the mananged object context is done by simply calling insertObject(). Sometimes, when inserting new data, you may not know whether the object has been saved before. For these situations, use findOrCreateInContext(moc: NSManagedObjectContext, matchingPredicate predicate: NSPredicate, configure: Self -> ()) -> Self. This acts very similarly to findOrFetchInContext but will create an object if no object is found in the database to match the given predicate.

let moc:NSManagedObjectContext = ...

// Insert directly
let newPost: Post = moc.insertObject()

// Insert when object may already exist in the database
let predicate = NSPredicate(format: "id == %@", "3003")
let newOrExistingPost = Post.findOrCreateInContext(moc: moc, matchingPredicate: predicate) { (editableObj) in
    // Configure the editableObj here...
}

Saving Objects

Once all changes have been made, you can save the context by calling saveOrRollback(). This function attempts to save all the changes, but if the command fails, it will rollback the changes. To perform a specific set of changes to be saved to the context right away, performChanges(block:()->()) is preferred. Here, all of your changes are wrapped in a single block. After they're performed the context is saved.

Creating the Main Context

To create the main context, you call createMainContext(modelStoreName: String, bundles: [NSBundle]?). This function sets up the Core Data stack and returns the main context. This would typically be called in the AppDelegate and then passed into the landing view controller.