What if I want to integrate CoreData later?

I actually use Realm more often. But don’t you feel like this sometimes? What if I want to use Core Data later? What if a cool new Core Data feature comes out and my project needs to be migrated? So I did some research and found it to be very easy. However, other blogs did not explain it as easily as I did, and there were too many additional explanations, so I couldn’t get the gist of it.

What we usually do when using CoreData

Enable Core Data when creating the project

Oh, I forgot to check “Use Core Data”!

Let’s assume you forgot to check “Use Core Data”

Don’t worry. It’s really easy to integrate.

1) Create Data Model

Create Data Model Manually

I named it “Posts”. Think of it as Database.

2) Add Core Data Stack Code

Core Source for using Core Data

Wow. This really looks similar when you create a project with “Use Core Data” marked. That’s right. Because what we need is persistentContainer and saveContext() method.

You can create your own class or attach this code snippet on AppDelegate depending on your taste. I personally added on AppDelegate.swift.

#Note!!!

Posts!!!

let container = NSPersistentContainer(name: “Posts”)

Posts is the database name we created!!! It should match when instantiating NSPersistentContainer

3) Define your model in xcdatamodel (Optional)

Integration part is already finished at Step 2, but if you want to follow along, read more!

• Go to Posts.xcdatamodel

Go to Posts.xcdatamodel

(1) Create Entity

Add your entity. Consider Entity as Table

(2) Define your own model

Define your own model

I made three properties. If I describe it with code, it would look like this.

// You don't need to write this code!!! 
// It's already auto-generated by CoreData
// It's just an example to make you understand.
class Post {
  var title: String
  var content: String 
  var created: Date
}

#Warning!

You don’t need to write any code to generate model.

“CoreData auto-generates model class for you”.

4) CRUD (Optional)

CRUD stands for Create, Read, Update, Delete. It’s a common acronym for developers. This is the concept that you will learn first when you handle any kind of databases.

(1) Create

Create Operation

As you can see, we need persistent context and saveContext() to use CoreData.

(2) READ

Read Operation

We need only persistentContainer to read data.

(3) Update

Update Operation

Call saveContext() after you changed model class.

(4) Delete

Delete Operation

After you deleted model object, you should call saveContext()

5) CoreData Common Workflow

1. What you need is persistentContainer and saveContext().
2. When you load data and need built-in functionalities, you need to obtain context, which can be accessed by persistentContainer.
3. When you changed model object, always call saveContext()

Conclusion

It’s really not that hard. What you need is just persistentContainer and saveContext() with xcdatamodel files you create. So, don’t worry if you didn’t enable CoreData when creating a project.

Check this repository!

GitHub - paigeshin/CoreData-CRUD