OSとSWIFTラーニング-データベースの設定とデータの保存(英語)

We are going to use Cloud Firestore
(There is Cloud Firestore & Realtime Databse)

Head to your project console, and "create database"

Start in test mode

Make sure the necessary pods are installed

The next step is to initialize the Cloud Firestore

(must write in AppDelegate.swift)

Now, we made our database → We are now ready to put in data

In my app, since I am developing a chat app, we need to tap into the "current user"online.

→ If we check the Firebase documents, we can see that we are able to get the currently signed-in user by using the below code:

if Auth.auth().currentUser != nil {
  // User is signed in.
  // ...
} else {
  // No user is signed in.
  // ...
}

(currentUser is an optional, so we need to check if it is nil or not)
→ First, you need a reference to the DB to actually access it within the view controller

Now how do we add data to Firestore? → Check the documents as well

→ We access the db using the collection (dictionary).

Since this is a chat app, we ultimately need the "sender"and the "body"to be saved to the DB.

→ messageTextfield.text is the chat message that the user types, and Auth.auth().currentUser?.email is the currently signed in user's email
→ Since both are Optionals, we need to optionally bind the values into separate constants (messageBody and messageSender)
→ Once optional binding is successful, we can then tap in to the DB using the code below.

@IBAction func sendPressed(_ sender: UIButton) {
        
        // Optional Binding -> Checking if both are not nil first
        if let messageBody = messageTextfield.text, let messageSender = Auth.auth().currentUser?.email{
            
            // Then, we send the data to the DB
            db.collection(K.FStore.collectionName).addDocument(data: [K.FStore.senderField: messageSender, K.FStore.bodyField: messageBody]) { (error) in
                if let e = error{
                    print("There was an issue saving data to firestore, \(e)")
                }
                else{
                    print("Successfully saved data")
                }
            }
        }
    }

(Constants.swift)
→ Notice we are sending the data in a Dictionary format.

If the data is saved successfully without errors, the DB will look like this.

db.collection(K.FStore.collectionName).addDocument(data: [K.FStore.senderField: messageSender, K.FStore.bodyField: messageBody])

→ Take a look at the code above.
K.Fstore.collection name is the name of the newly created "collection"in Cloud Firestore. Then, we add a document (addDocument) within this newly created collection, with a Dictionary that we have configured.