What is core data and how do I use it?
Today, Core Data is available on iOS, tvOS, macOS, and watchOS. Core Data is the M in MVC, the model layer of your application. Even though Core Data can persist data to disk, data persistence is actually an optional feature of the framework. Core Data is first and foremost a framework for managing an object graph.
What is apple core data programming?
Apple Developer Core Data Programming Guide. Core Data is an object graph and persistence framework provided by Apple in the macOS and iOS operating systems. It was introduced in Mac OS X 10.4 Tiger and iOS with iPhone SDK 3.0.
What is core data in Salesforce?
Core Data is a framework that you use to manage the model layer objects in your application. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence. Core Data typically decreases by 50 to 70 percent the amount of code you write to support the model layer.
What is core data in MVC?
Core Data is the M in MVC, the model layer of your application. Even though Core Data can persist data to disk, data persistence is actually an optional feature of the framework. Core Data is first and foremost a framework for managing an object graph. You've probably heard and read about Core Data before watching this episode.
What is core data?
Core Data is a framework that you use to manage the model layer objects in your application. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence.
What is managed object validation?
Managed objects extend the standard key-value coding validation methods to ensure that individual values lie within acceptable ranges, so that combinations of values make sense.
How much does core data decrease?
Core Data typically decreases by 50 to 70 percent the amount of code you write to support the model layer. This is primarily due to the following built-in features that you do not have to implement, test, or optimize:
What is optional integration with the application’s controller layer?
Optional integration with the application’s controller layer to support user interface synchronization.
What is maintenance of change propagation?
Maintenance of change propagation, including maintaining the consistency of relationships among objects.
What is core data?
It is actually a framework that lets developers store (or retrieve) data in database in an object-oriented way. With Core Data, you can easily map the objects in your apps to the table records in the database without even knowing any SQL. To illustrate the concept, let’s begin and create your first app using Core Data.
How to create a storyboard in iOS?
The next thing we need to do is to create the Storyboard that defines the views of our app. Navigate to File > New > New File and choose Storyboard in the User Interface template. Click next and select the iPhone device family, click create .
What is the focus of the tutorial?
The focus of the tutorial is to provide a practical introduction of Core Data framework. I expect you’ve already gone through our tutorials about Storyboard and UITableView. I will not give in-depth explanation about how to create view controller in Storyboard but you can always refer to the earlier tutorials to gain better understanding.
How to add a button to a table view?
First, drag a Table View Controller and embed it in a Navigation Controller. Drag a button to the top-right part of navigation bar and set the identifier as “Add”. This will automatically change the button to a “+” button. Next, select the prototype cell and change its style to “Right Detail”.
What is persistence on iPhone?
What I mean by persistence is to make data that’s in your apps stay around between application launches. Persistence lets users store persistent data and also retrieve it, so that users don’t have to reenter all their data each time they use their applications. There are multiple ways to store data in iOS devices but most of them aren’t good enough to store a complicated data. They are usually used to save settings or to preload some data such as “Property List” and “Archiving Objects”. So that’s why we’ll go through Core Data to see how you can utilize it to manage data in database.
What is my store app?
This app is called My Store. It is a very simple app that stores all devices you have by collecting the name, version, company.
What is managed object model?
Managed Object Model – It describes the schema that you use in the app. If you have a database background, think of this as the database schema. However, the schema is represented by a collection of objects (also known as entities). In Xcode, the Managed Object Model is defined in a file with the extension . xcdatamodeld. You can use the visual editor to define the entities and their attributes, as well as, relationships.
What is an EOF?
EOF was an object-relational mapping for high-end SQL database engines such as Microsoft SQL Server and Oracle . EOF's purpose was twofold: first, to connect to the database engine and hide the implementation details; second, to read the data out of the relational format and translate that into a set of objects. Developers typically interacted only with the objects, which simplified development of complex programs, at the cost of some setup to map the data to the objects. The EOF object model was deliberately designed to make the resulting programs work in a document-like fashion; the user could edit the data locally in memory, and then write out all changes with a single Save command.
What is EOF in NeXTSTEP?
Throughout its history, EOF contained a number of bits of useful code that were not otherwise available under NeXTSTEP / OpenStep. For instance, EOF required the ability to track which objects were dirty so the system could later write them out. This was presented to the developer not only as a document-like system, but also in the form of an unlimited Undo command stack, with each command applied to the data represented as an undoable action. Many developers complained that this state management code was far too useful to be isolated in EOF, and it was later moved into the Cocoa API during the transition to Mac OS X .
What is core data?
Core Data is an object graph and persistence framework provided by Apple in the macOS and iOS operating systems. It was introduced in Mac OS X 10.4 Tiger and iOS with iPhone SDK 3.0. It allows data organized by the relational entity–attribute model to be serialized into XML, binary, or SQLite stores. The data can be manipulated using higher level objects representing entities and their relationships. Core Data manages the serialized version, providing object lifecycle and object graph management, including persistence. Core Data interfaces directly with SQLite, insulating the developer from the underlying SQL.
How is core data organized?
Core Data is organized into a large hierarchy of classes, though interaction is only prevalent with a small set of them.
Can you read Xcode data model files?
If you have the Xcode Data Model file, you can read and write files in that format freely. Unlike EOF, though, Core Data is not currently designed for multiuser or simultaneous access unless you use ODBC framework. Schema migration is also non-trivial, almost always requiring code.
Can you write your own SQL?
Unlike EOF, it is not possible to write your own SQL, as the underlying store may not be SQL-based. Recently, Core Data store for ODBC has been made available in ODBC framework. Core Data schemas are standardized. If you have the Xcode Data Model file, you can read and write files in that format freely.
Is schema migration a requirement?
Schema migration is also non-trivial, almost always requiring code. If other developers have access to and depend upon your data model, you may need to provide version translation code in addition to a new data model if your schema changes.
Why does core data only work on objects?
Core Data can only do its magic because it keeps the object graph it manages in memory. This means that it can only operate on records once they are in memory. This is very different from performing a SQL query on a database. If you want to delete thousands of records, Core Data first needs to load each record into memory. It goes without saying that this results in memory and performance issues if done incorrectly.
What is object graph?
An object graph is nothing more than a collection of objects that are connected with one another. The Core Data framework excels at managing complex object graphs.
What is core data?
Core Data is an excellent choice if you want a solution that manages the model layer of your application. Developers new to Core Data are often confused by the differences between SQLite and Core Data.
Is Core Data good for graphing?
For applications that need to manage a complex object graph, Core Data is a great fit. If you only need to store a handful of unrelated objects, then you may be better off with a lightweight solution or the user defaults system.
Is core data a database?
You've probably heard and read about Core Data before watching this episode. That means that you may already know that Core Data is not a database and that it manages your application's object graph. Both statements are true. But what do they mean?
Is core data used in every application?
Even though Core Data is a perfect fit for a wide range of applications, not every application should use Core Data.
Managing an Object Graph
As I mentioned earlier, Core Data is first and foremost an object graph manager. An object graph is nothing more than a collection of objects that are connected with one another. The Core Data framework excels in managing such an object graph.
When to Use Core Data
Even though Core Data is a perfect fit for a wide range of applications, not every application should use Core Data. Are you in need of a lightweight model layer? Then Core Data should not be your first choice. There are many lightweight libraries that provide this type of functionality.
SQLite or Core Data
Developers new to Core Data are often confused by the differences between SQLite and Core Data. If you wonder whether you need SQLite or Core Data, then you are asking the wrong question. Remember that Core Data is not a database.
Drawbacks
Even though Core Data is a fantastic framework, there are several drawbacks. These drawbacks are directly related to the nature of Core Data. Core Data can only do its magic because it keeps the object graph it manages in memory. This means that it can only operate on records once they are in memory.
Should You Use Core Data
For applications that need to manage a complex object graph, Core Data is a great fit. If you only need to store a handful of unrelated objects, then you may be better off with a lightweight solution or the user defaults system.
CORE Data Is Not A Database
Creating A Sample App with CORE Data
- First let’s create a project with Core Data. Open Xcode and create a new Project, choose the templateEmpty Applicationas shown below. At the next screen, enter MyStore as a name of the project, select iPhone in Devices family and don’t forget to select the options Use Storyboards, Use Core Data, Use Automatic Reference Counting. Press next and create.
CORE Data Stack
- Before we start working on the project, you first have to understand the Core Data Stack: Managed Object Model – It describes the schema that you use in the app. If you have a database background, think of this as the database schema. However, the schema is represented by a collection of objects (also known as entities). In Xcode, the Managed Object Model is defined in …
Defining Managed Object Model
- Let’s move on to build the app. The first step is to open the Data Model named MyStore.xcdatamodeld and define the object model. Here we’ll define a Device entity that will be used to store the device information to database. To create an entity, click the + button in the bottom-left of the editor view and name the entity as Device. Once you create a new entity, you n…
Designing The User Interface
- The next thing we need to do is to create the Storyboard that defines the views of our app. Navigate to File > New > New File and choose Storyboard in the User Interfacetemplate. Click next and select the iPhone device family, click create. Once created, make sure to set the “Storyboard” you’ve just created as the main storyboard in the project setting. Also don’t forget to delete all th…
Diving Into CORE Data
- With the user interface, it’s time to go into the details of Core Data. Apparently, there are a couple of areas we have to implement: 1. Save device information in the Detail View Controller 2. Fetch device information from persistent store (i.e. SQLite database) and populate the data into Table View Controller We’ll look into the implementation one by one.
What’s Coming Next
- It’s a lengthy tutorial but we try to elaborate the implementation as detail as possible so everyone can follow. As you can see, with Core Data, you don’t have to care about SQL to save and retrieve data from database. Everything is done behind the scene. This tutorial kicks off the first part of Core Data series. Later we’ll talk more about object relationship. Lastly, let me end the tutorial wi…
Overview
Core Data is an object graph and persistence framework provided by Apple in the macOS and iOS operating systems. It was introduced in Mac OS X 10.4 Tiger and iOS with iPhone SDK 3.0. It allows data organized by the relational entity–attribute model to be serialized into XML, binary, or SQLite stores. The data can be manipulated using higher level objects representing entities and their relationships. Core Data manages the serialized version, providing object lifecycle and object graph management, …
Usage
Core Data describes data with a high level data model expressed in terms of entities and their relationships plus fetch requests that retrieve entities meeting specific criteria. Code can retrieve and manipulate this data on a purely object level without having to worry about the details of storage and retrieval. The controller objects available in Interface Builder can retrieve and manipulate these entities directly. When combined with Cocoa bindings the UI can display man…
Storage formats
Core Data can serialize objects into XML, binary, or SQLite for storage. With the release of Mac OS X 10.5 Leopard, developers can also create their own custom atomic store types. Each method carries advantages and disadvantages, such as being human readable (XML) or more memory efficient (SQLite).
This portion of Core Data is similar to the original Enterprise Objects Framework (EOF) system, i…
History and genesis
Core Data owes much of its design to an earlier NeXT product, Enterprise Objects Framework (EOF).
EOF was an object-relational mapping for high-end SQL database engines such as Microsoft SQL Server and Oracle. EOF's purpose was twofold: first, to connect to the database engine and hide the implementation details; second, to read the data out of the relational format and translate that into a set of objects. Developers typically interacted only with the objects, which simplifi…
Core Data owes much of its design to an earlier NeXT product, Enterprise Objects Framework (EOF).
EOF was an object-relational mapping for high-end SQL database engines such as Microsoft SQL Server and Oracle. EOF's purpose was twofold: first, to connect to the database engine and hide the implementation details; second, to read the data out of the relational format and translate that into a set of objects. Developers typically interacted only with the objects, which simplified devel…
Notes
1. ^ Apple, "Core Data Tutorial for iPhone OS".
2. ^ Apple, "Core Data Programming Guide".
3. ^ Zarra, Core Data.
4. ^ Stevenson, "Core Data Class Overview"
External links
• Apple Inc. (2018). "Core Data". Retrieved from https://developer.apple.com/documentation/coredata
• Apple Inc. (2009). "Web Objects Tutorial". Retrieved from https://developer.apple.com/legacy/mac/library/documentation/DeveloperTools/Conceptual/WO…
What Is CORE Data?
How Does CORE Data Vary from Sqlite?
- Developers new to Core Data are confused by the differences between SQLite and Core Data. If you are confused about whether you need SQLite or Core Data, then you’re asking the wrong question. Remember that Core Data isn’t a database.
Getting Started with Tutorial
- In order to understand the basics of Core Data, let’s create a single view iOS app and select the Core Data module. We have created a demo project with Core Data Framework support. There are two notable changes in this Xcodetemplate you can easily observe which are : 1. The new CoreDataDemo.xcdatamodeld 2. The AppDelegate.swift file with Core Data Stack code
What to Do Next?
- We have saved and retrieved data from Core data but these are basic operations to start with, we can do a lot more things with Core Data. We can modify, delete, track data changes, adding predicates. And it’s fun to do all these things with Core Data. If you face any technical difficulties feel free to contact our technical experts, we would love to resolve your queries. You can contac…