Swift: Add Firebase to Your Project — Chapter 1

Section Overview:
1. Introduction 
2. Installing Firebase
3. Configure Firebase
4. Saving Data to Firebase
5. Reading Data from Firebase
6. Updating and Deleting

What is Firebase?

Firebase is a Google-backed service that provide us with a cloud based infrastructure that allows us to save and retrieve the data from Google web services. That let us not need to maintain our servers and write server site code because the guy Firebase is taking care of these for us!

Firebase has 3 core services:

• a realtime database
• user authentication
• hosting

Installing Firebase with Cocoapods

First, head over to https://firebase.google.com/ > sign in with your google account > go to console > create a project > add Firebase to your iOS app (follow Google instructions to complete. Note: In step 2, I checked “Copy items if needed” when adding it to my Xcode project because I want to delete the download folder right after. When adding Firebase SDK, you can open your Podfile and add the following pods.)

Tips on terminal: pod init > open Podfile -a Xcode > add the following pods:

pod ‘Firebase’
pod 'Firebase/Core'
pod ‘Firebase/Auth’
pod ‘Firebase/Database’
pod ‘SVProgressHUD’
pod ‘ChameleonFramework’

> pod install

Integrate Firebase into Our Project

1. Open up the workspace, import Firebase, initialize and configure the Firebase in AppDelegate

Note: What does AppDelegate do? AppDelegate handles application lifecycle events — i.e., responding to the app being launched, backgrounded, foregrounded, receiving data, etc.

2. Go to Authentication > Click “Sign-in method” > enable Email/ Password

3. change Database Rules as following to make everyone assess the database without restriction

{
  "rules": {
    ".read": true,
    ".write": true
  }
}

Read and Write Data into Firebase

Go to your ViewController > import Firebase> call the reference of database

let planItemsReference = Database.database().reference(withPath: “to-do list”)

let itemRef = self.planItemsReference.child(textField.text!.lowercased())
// Save value by passing in a dictionary
let values: [String: Any] = [ "name": textField.text!.lowercased(), "addedByUser": self.user.email, "completed": "not yet"]
itemRef.setValue(values)

created a snapshot of firebase:

planItemsReference.observe(.value, with: {
  snapshot in
  print(snapshot)
})

planItemsReference.child(“sample”).observe(.value, with: {
    snapshot in
    let values = snapshot.value as! [String: AnyObject]
    let name = values[“name”] as! String
    let addedBy = values[“addedByUser”] as! String
    let completed = values[“completed”] as! Bool
    print(“names: \(name)”)
    print(“added by: \(addedBy)”)
    print(“completed \(completed)”)
})

//load the list of PlanItem to TableViewController
planItemsReference.observe(.value, with: {
    snapshot in
    var newItems: [PlanItem] = []
    for item in snapshot.children {
        let planItem = PlanItem(snapshot: item as! DataSnapshot)
        newItems.append(planItem)
    }
    self.items = newItems
    self.tableView.reloadData()
})

Updating and Deleting

Updating

Whenever tapping on the list item, the item updates to “sleep” like so:

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    guard let cell = tableView.cellForRow(at: indexPath) else   { return }
    var listItem = items[indexPath.row]
    let values: [String: Any] = [“name”: “sleep”]
    listItem.ref?.updateChildValues(values)
    tableView.reloadData() 
}

Deleting

Delete the data from Firebase and UITableView:

Method 1: remove the value

override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
        let listItem = items[indexPath.row]
        listItem.ref?.removeValue()
        items.remove(at: indexPath.row)
        tableView.reloadData()
    }   
}

Method 2: set the value to nil

override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
        let listItem = items[indexPath.row]
        listItem.ref?.setValue(nil)
        items.remove(at: indexPath.row)
        tableView.reloadData()
    }
}

Querying Data

Get the all the items created by a username or get a list of items that have been marked as completed. Like updates, querying starts from a reference. Queries return Database Query Objects which you can observe like references.

planItemsReference.queryOrdered(byChild: “completed”).observe(.value, with: {
    snapshot in
    var newItems: [PlanItem] = []
    for item in snapshot.children {
        let plan = PlanItem(snapshot: item as! DataSnapshot)
        newItems.append(plan)
    }
    self.items = newItems
    self.tableView.reloadData()
})

🔍download the project to practice: https://github.com/vicky-kuo-contact/Planner

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