How to Develop a CRUD App for iOS using Swift?

27min
Overview
This walkthrough will guide you in building a simple CRUD (Create, Read, Update, Delete) application for iOS. 
Using Back4app as your cloud backend, you'll learn how to configure your project, design a flexible data model, and implement CRUD functionality with Swift. 
This tutorial demonstrates how to integrate your iOS app with Back4app, leveraging either the Parse iOS SDK or REST API, ensuring smooth data management and secure authentication.
Initially, you'll set up a Back4app project—named Basic-CRUD-App-iOS—that provides a scalable, non-relational database for your app. You will define your data structures by creating classes and fields either manually or by using Back4app’s AI Agent.
Next, you’ll explore how to manage your backend using the intuitive Back4app Admin App, a drag-and-drop tool designed to simplify data manipulation. 
Finally, you’ll connect your iOS application with the backend, using either the Parse iOS SDK (when applicable) or REST/GraphQL API calls, and incorporate secure user authentication.
By the end of this guide, you will have built a production-ready iOS application that performs core CRUD operations, including secure user sign-in and data handling.
Main Insights
Learn to create an iOS CRUD application with an efficient backend.
Understand how to architect a scalable backend and connect it seamlessly with an iOS app.
Discover how to use the Back4app Admin App for streamlined data creation, retrieval, modification, and deletion.
Explore options for containerized deployment and further enhancements for your iOS project.
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Prerequisites
Before you begin, ensure you have:
A Back4app account with an active project.
Need help? See Getting Started with Back4app.
An iOS development setup.
Use Xcode (version 12 or later) and ensure your development environment is up-to-date.
A solid grasp of Swift, object-oriented programming, and REST API fundamentals.
Refer to the Swift documentation for more details.
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Step 1 – Setting Up Your Project
Creating a New Back4app Project
Log in to your Back4app account.
Click on the “New App” button from your dashboard.
Name your project: Basic-CRUD-App-iOS and follow the on-screen instructions to complete the setup.
Create New Project
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After the project is created, it will appear in your dashboard, laying the foundation for your backend configuration.
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Step 2 – Crafting Your Data Model
Defining Your Data Structures
For this iOS CRUD application, you will establish several classes (collections) in your Back4app project. Below are the primary classes and their fields required to support your CRUD operations.
1. Items Class
This class will store information about each item.
Field
Data Type
Description
_id
ObjectId
Automatically generated unique identifier.
title
String
The name or title of the item.
description
String
A brief summary or details about the item.
createdAt
Date
Timestamp marking when the item was created.
updatedAt
Date
Timestamp marking the last update to the item.
2. Users Class
This class manages user credentials and authentication data.
Field
Data Type
Description
_id
ObjectId
Auto-generated unique identifier.
username
String
Unique identifier for the user.
email
String
Unique email address of the user.
passwordHash
String
Encrypted password for secure authentication.
createdAt
Date
Timestamp of when the account was created.
updatedAt
Date
Timestamp of the latest account update.
You can define these classes and fields directly in the Back4app dashboard.
Create New Class
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You can add columns by selecting a data type, naming the field, setting a default value, and marking it as required if needed.
Create Column
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Utilizing the Back4app AI Agent for Schema Configuration
The integrated AI Agent in your dashboard can automatically generate your data schema from a description. This helps streamline the setup and ensures your data model supports all necessary CRUD operations.
How to Use the AI Agent:
Open the AI Agent:
Access it via your project settings in the Back4app dashboard.
Describe Your Data Model:
Provide a comprehensive prompt detailing the classes and their respective fields.
Review and Implement:
Examine the proposed schema and confirm to apply the configuration.
Example Prompt
Text
Create the following classes in my Back4app project:

1) Class: Items
- Fields:
  - _id: ObjectId (auto-generated)
  - title: String
  - description: String
  - createdAt: Date (auto-generated)
  - updatedAt: Date (auto-updated)

2) Class: Users
- Fields:
  - _id: ObjectId (auto-generated)
  - username: String (unique)
  - email: String (unique)
  - passwordHash: String
  - createdAt: Date (auto-generated)
  - updatedAt: Date (auto-updated)
Create the following classes in my Back4app project:

1) Class: Items
- Fields:
  - _id: ObjectId (auto-generated)
  - title: String
  - description: String
  - createdAt: Date (auto-generated)
  - updatedAt: Date (auto-updated)

2) Class: Users
- Fields:
  - _id: ObjectId (auto-generated)
  - username: String (unique)
  - email: String (unique)
  - passwordHash: String
  - createdAt: Date (auto-generated)
  - updatedAt: Date (auto-updated)
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This AI-powered approach saves time and ensures a consistent, optimized data structure for your iOS app.
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Step 3 – Launching the Admin App & Managing CRUD Operations
Overview of the Admin App
The Back4app Admin App provides a no-code interface to efficiently manage your backend data. Its user-friendly drag-and-drop features simplify the process of creating, reading, updating, and deleting records.
Enabling the Admin App
Go to the “More” section in your Back4app dashboard.
Select “Admin App” and click “Enable Admin App.”
Set up your admin credentials by creating the initial admin account, which will also establish system roles (such as B4aAdminUser).
Enable Admin App
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After activation, log into the Admin App to manage your data.
Admin App Dashboard
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Managing Data with the Admin App
Within the Admin App you can:
Insert Records: Use the “Add Record” feature within any class (e.g., Items) to introduce new entries.
Review/Edit Records: Select a record to view its details or modify its fields.
Remove Records: Delete entries that are no longer needed.
This intuitive interface simplifies backend management and enhances productivity.
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Step 4 – Connecting Your iOS App with Back4app
With your backend ready, the next step is to link your iOS application to Back4app.
Option A: Utilizing the Parse iOS SDK
Install the Parse iOS SDK:
You can integrate the SDK using Swift Package Manager or CocoaPods. For CocoaPods, add the following to your Podfile:
Ruby
pod 'Parse'
pod 'Parse'
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Initialize Parse in Your App:
In your AppDelegate, configure Parse by inserting the following code:
Swift
// AppDelegate.swift
import UIKit
import Parse

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        let configuration = ParseClientConfiguration {
            $0.applicationId = "YOUR_APPLICATION_ID"
            $0.clientKey = "YOUR_IOS_KEY" // Replace with your iOS key
            $0.server = "https://parseapi.back4app.com"
        }
        Parse.initialize(with: configuration)
        return true
    }

    // ...
}
// AppDelegate.swift
import UIKit
import Parse

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        let configuration = ParseClientConfiguration {
            $0.applicationId = "YOUR_APPLICATION_ID"
            $0.clientKey = "YOUR_IOS_KEY" // Replace with your iOS key
            $0.server = "https://parseapi.back4app.com"
        }
        Parse.initialize(with: configuration)
        return true
    }

    // ...
}
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Implement CRUD Operations:
Create a service class in Swift to handle your data operations. For example, a service to fetch and display items:
Swift
// ItemsService.swift
import Foundation
import Parse

class ItemsService {
    func fetchItems(completion: @escaping ([PFObject]?) -> Void) {
        let query = PFQuery(className: "Items")
        query.findObjectsInBackground { (objects, error) in
            if let error = error {
                print("Error retrieving items: \(error.localizedDescription)")
                completion(nil)
            } else {
                completion(objects)
            }
        }
    }

    func addItem(title: String, description: String) {
        let item = PFObject(className: "Items")
        item["title"] = title
        item["description"] = description
        item.saveInBackground { (success, error) in
            if success {
                print("Item successfully created.")
            } else if let error = error {
                print("Creation error: \(error.localizedDescription)")
            }
        }
    }

    func modifyItem(objectId: String, newTitle: String, newDescription: String) {
        let query = PFQuery(className: "Items")
        query.getObjectInBackground(withId: objectId) { (item, error) in
            if let item = item {
                item["title"] = newTitle
                item["description"] = newDescription
                item.saveInBackground { (success, error) in
                    if success {
                        print("Item updated.")
                    } else if let error = error {
                        print("Update error: \(error.localizedDescription)")
                    }
                }
            } else if let error = error {
                print("Error finding item: \(error.localizedDescription)")
            }
        }
    }

    func removeItem(objectId: String) {
        let query = PFQuery(className: "Items")
        query.getObjectInBackground(withId: objectId) { (item, error) in
            if let item = item {
                item.deleteInBackground { (success, error) in
                    if success {
                        print("Item deleted.")
                    } else if let error = error {
                        print("Deletion error: \(error.localizedDescription)")
                    }
                }
            } else if let error = error {
                print("Error locating item: \(error.localizedDescription)")
            }
        }
    }
}
// ItemsService.swift
import Foundation
import Parse

class ItemsService {
    func fetchItems(completion: @escaping ([PFObject]?) -> Void) {
        let query = PFQuery(className: "Items")
        query.findObjectsInBackground { (objects, error) in
            if let error = error {
                print("Error retrieving items: \(error.localizedDescription)")
                completion(nil)
            } else {
                completion(objects)
            }
        }
    }

    func addItem(title: String, description: String) {
        let item = PFObject(className: "Items")
        item["title"] = title
        item["description"] = description
        item.saveInBackground { (success, error) in
            if success {
                print("Item successfully created.")
            } else if let error = error {
                print("Creation error: \(error.localizedDescription)")
            }
        }
    }

    func modifyItem(objectId: String, newTitle: String, newDescription: String) {
        let query = PFQuery(className: "Items")
        query.getObjectInBackground(withId: objectId) { (item, error) in
            if let item = item {
                item["title"] = newTitle
                item["description"] = newDescription
                item.saveInBackground { (success, error) in
                    if success {
                        print("Item updated.")
                    } else if let error = error {
                        print("Update error: \(error.localizedDescription)")
                    }
                }
            } else if let error = error {
                print("Error finding item: \(error.localizedDescription)")
            }
        }
    }

    func removeItem(objectId: String) {
        let query = PFQuery(className: "Items")
        query.getObjectInBackground(withId: objectId) { (item, error) in
            if let item = item {
                item.deleteInBackground { (success, error) in
                    if success {
                        print("Item deleted.")
                    } else if let error = error {
                        print("Deletion error: \(error.localizedDescription)")
                    }
                }
            } else if let error = error {
                print("Error locating item: \(error.localizedDescription)")
            }
        }
    }
}
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Option B: Using REST or GraphQL
If the Parse iOS SDK does not suit your needs, you can execute CRUD operations via REST calls. For instance, to fetch items using REST in Swift:
Swift
import Foundation

class RestClient {
    func retrieveItems() {
        guard let url = URL(string: "https://parseapi.back4app.com/classes/Items") else { return }

        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.addValue("YOUR_APPLICATION_ID", forHTTPHeaderField: "X-Parse-Application-Id")
        request.addValue("YOUR_REST_API_KEY", forHTTPHeaderField: "X-Parse-REST-API-Key")

        URLSession.shared.dataTask(with: request) { data, response, error in
            if let error = error {
                print("Error fetching items: \(error.localizedDescription)")
                return
            }
            guard let data = data else { return }
            if let json = try? JSONSerialization.jsonObject(with: data, options: []) {
                print("Fetched items: \(json)")
            }
        }.resume()
    }
}
import Foundation

class RestClient {
    func retrieveItems() {
        guard let url = URL(string: "https://parseapi.back4app.com/classes/Items") else { return }

        var request = URLRequest(url: url)
        request.httpMethod = "GET"
        request.addValue("YOUR_APPLICATION_ID", forHTTPHeaderField: "X-Parse-Application-Id")
        request.addValue("YOUR_REST_API_KEY", forHTTPHeaderField: "X-Parse-REST-API-Key")

        URLSession.shared.dataTask(with: request) { data, response, error in
            if let error = error {
                print("Error fetching items: \(error.localizedDescription)")
                return
            }
            guard let data = data else { return }
            if let json = try? JSONSerialization.jsonObject(with: data, options: []) {
                print("Fetched items: \(json)")
            }
        }.resume()
    }
}
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Integrate these API methods into your Swift classes as necessary.
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Step 5 – Securing Your Backend
Configuring Access Control Lists (ACLs)
Safeguard your data by setting up ACLs. For instance, to create an item that only its owner can access:
Swift
import Parse

func createPrivateItem(title: String, description: String, owner: PFUser) {
    let item = PFObject(className: "Items")
    item["title"] = title
    item["description"] = description

    let acl = PFACL()
    acl.setReadAccess(true, for: owner)
    acl.setWriteAccess(true, for: owner)
    acl.publicReadAccess = false
    acl.publicWriteAccess = false
    item.acl = acl

    item.saveInBackground { (success, error) in
        if success {
            print("Private item successfully created.")
        } else if let error = error {
            print("Error saving item: \(error.localizedDescription)")
        }
    }
}
import Parse

func createPrivateItem(title: String, description: String, owner: PFUser) {
    let item = PFObject(className: "Items")
    item["title"] = title
    item["description"] = description

    let acl = PFACL()
    acl.setReadAccess(true, for: owner)
    acl.setWriteAccess(true, for: owner)
    acl.publicReadAccess = false
    acl.publicWriteAccess = false
    item.acl = acl

    item.saveInBackground { (success, error) in
        if success {
            print("Private item successfully created.")
        } else if let error = error {
            print("Error saving item: \(error.localizedDescription)")
        }
    }
}
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Class-Level Permissions (CLPs)
Within the Back4app dashboard, adjust the CLPs for your classes to enforce default security measures. This ensures that only authenticated users or designated roles have access to specific data.
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Step 6 – Implementing User Authentication
Setting Up User Accounts
Back4app uses the built-in Parse User class to manage authentication. In your iOS application, handle user registration and login as illustrated below:
Swift
import Parse

class AuthService {
    func registerUser(username: String, password: String, email: String) {
        let user = PFUser()
        user.username = username
        user.password = password
        user.email = email

        user.signUpInBackground { (succeeded, error) in
            if succeeded {
                print("User registered successfully!")
            } else if let error = error {
                print("Registration failed: \(error.localizedDescription)")
            }
        }
    }

    func loginUser(username: String, password: String) {
        PFUser.logInWithUsername(inBackground: username, password: password) { (user, error) in
            if let user = user {
                print("Logged in as: \(user.username ?? "Unknown")")
            } else if let error = error {
                print("Login error: \(error.localizedDescription)")
            }
        }
    }
}
import Parse

class AuthService {
    func registerUser(username: String, password: String, email: String) {
        let user = PFUser()
        user.username = username
        user.password = password
        user.email = email

        user.signUpInBackground { (succeeded, error) in
            if succeeded {
                print("User registered successfully!")
            } else if let error = error {
                print("Registration failed: \(error.localizedDescription)")
            }
        }
    }

    func loginUser(username: String, password: String) {
        PFUser.logInWithUsername(inBackground: username, password: password) { (user, error) in
            if let user = user {
                print("Logged in as: \(user.username ?? "Unknown")")
            } else if let error = error {
                print("Login error: \(error.localizedDescription)")
            }
        }
    }
}
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A similar approach can be implemented for managing sessions, password resets, and other authentication features.
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Step 7 – Conclusion and Future Enhancements
Congratulations! You have successfully built an iOS-based CRUD application that integrates with Back4app. 
You configured a project named Basic-CRUD-App-iOS, designed the Items and Users classes, and managed your data using the Back4app Admin App. 
Additionally, you connected your iOS app through the Parse SDK (or via REST/GraphQL) and implemented essential security measures.
Future Steps:
Expand the Application:
Consider adding features like advanced filtering, detailed item views, or real-time updates.
Enhance Backend Capabilities:
Experiment with cloud functions, third-party API integrations, or more granular role-based access control.
Deepen Your Expertise:
Visit the Back4app documentation and explore additional tutorials to further optimize your application.
Happy coding and best wishes on your journey to building robust iOS applications!
Field	Data Type	Description
_id	ObjectId	Automatically generated unique identifier.
title	String	The name or title of the item.
description	String	A brief summary or details about the item.
createdAt	Date	Timestamp marking when the item was created.
updatedAt	Date	Timestamp marking the last update to the item.
Field	Data Type	Description
_id	ObjectId	Auto-generated unique identifier.
username	String	Unique identifier for the user.
email	String	Unique email address of the user.
passwordHash	String	Encrypted password for secure authentication.
createdAt	Date	Timestamp of when the account was created.
updatedAt	Date	Timestamp of the latest account update.
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