Firestore makes use of collections as storage structure. Each collection has one or more documents which are made up of attributes that contain the actual data.

Structure of firestore storage

Structure with examples

Similarly, firestore can store many collections.

References

A reference can be created for collection as well as document. Creating a reference does not perform any network operation, it only point to a location in the database.

For e.g reference to a collection

let mealCollectionRef = db.collection("Meal")

For e.g reference to a document

let mealOneDocumentRef = db.collection("Meal").document("Meal 1")

Note: A document can have a collection too. For instance, a review needs data from the reviewer and the review itself.

• Meals

  • Meal one

    • title : "Burgers"

    • reviews

      • review one

      from : "alex"

      review : "Good"

      • review two

      from : "tom"

      review : "bad"

  • Meal Two

In the above, we have reviews as a sub-collection of document “Meal one” since reviews contain large number of data.

Referencing a sub-collection

let reviewRef = db.collection("Meals").document("Meal one").collection("reviews").document("review one")

Note: sub-collections need to be deleted manually, even if the parent document and collection are deleted

Create references

Document reference with generated id

var docRef: DocumentReference? = nil

Collection Reference with generated id

var colRef: CollectionReference? = nil

Read Documents

Multiple documents

To fetch multiple documents in a collection, we use getDocuments().

getDocuments() returns documents in querySnapshot as a list.

querySnapshots contain several documents, from which we can extract several or one document.

db.collection("meals").getDocuments() { (querySnapshot, error)  in
	if let error = error {
		print("Error getting documents: \(error)")
	} else {
		let documents = querySnapshot!.documents
		print("\(documents)")
	}
}

// OUTPUT
//[, 
// , 
// , 
// , 
// , 
// , 
// , 
// , 
// , 
//]

Single document

To fetch a single document, we loop through the documents obtained from querySnapshots .documents.

db.collection("meals").getDocuments() { (querySnapshot, error) in
	if let error = error { 
		print(" Cannot fetch documents")
	} else {
		for document in querySnapshots!.documents {
		   print("\(document.data())")
	        }//for
	}//else
}//getDocument

Get data

Fetching data from a single document using .data from document

db.collection("meals").getDocuments() { (querySnapshot, error)  in
   if let error = error {
      print("Error getting documents: \(error)")
   } else {
        let documents = querySnapshot!.documents
	print("Documents list: \(documents)")
	for document in documents {
	    print("Data from document: \(document.data())")
	}
	    print("\(documents)")
    }//else
}//getDocuments()

	// OUTPUT
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]
//Data from document: ["title": burger, "price": 125.5, "quantity": 2]
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]
//Data from document: ["title": Pasta, "price": 467, "quantity": 6]
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]
//Data from document: ["title": Pizza, "price": 400, "quantity": 2]
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]
//Data from document: ["title": Mac and cheese, "price": 125, "quantity": 4]

Extracting single attributes

db.collection("meals").getDocuments() { (querySnapshot, error)  in
	if let error = error {
	   print("Error getting documents: \(error)")
	} else {
	  let documents = querySnapshot!.documents
	   //print("Documents list: \(documents)")
	  for document in documents {
	   //print("Data from document: \(document.data())")
		let data = document.data()
		let title = data["title"]
		let price = data["price"]
		let quantity = data["quantity"]
		print("title: \(title ?? "No title")")
		print("price: \(price ?? "No price")")
	        print("quantity: \(quantity ?? "No quantity")")	
           }//for			
	 }//else
}//getDocuments

   // OUTPUT
//title: Mac and cheese
//price: 125
//quantity: 4
//title: burger
//price: 125.5
//quantity: 2
//title: Pizza
//price: 400
//quantity: 2

Add data

Adding data with specific document id

let data: [String: Any] = [
		"title": "Grilled lobster",
		"price": 30,
		"quantity": 2,
		"type": "Dinner"
]

func pushData() {
	db.collection("meals").document("five").setData(data) { err in
		if let err = err {
			print("Error writing to document: \(err)")
		} else {
			print("Data successfully written to doc")
		}//else	
	}//setData
}//Push data

Adding data with auto-generated document id

docRef = db.collection("meals").addDocument(data: data) { err in
	if let err = err {
		print("Error adding document: \(err)")
	} else {
        	print("Document \(self.docRef!.documentID) added"). 		      
        }	
}

Adding data from classes/struct

public struct Place: Codable {
	let name: String
	let isCapital: Bool?
	let population: Int?
	
	enum CodingKeys: String, CodingKey {
		case name
		case isCapital = "capital"
		case population
	}//enum
}//struct

// In ObservableObject class
let places = Place(name: "China", isCapital: false, population: 1449323776)
do {
   try db.collection("Places").document("Asia").setData(from: places)		} catch let error {
   print("Error writing ro firestore \(error)")
}

Note: You may get an error “Extraneous argument label 'from:' in call”. This is because firestore makes use of an extension (FirebaseFirestoreSwift) to be able to save custom objects such as struct.

Fix: import FirebaseFirestoreSwift.

In case this is missing from your imports, just go to Targets → Frameworks, Libraries, and Embedded Content. Click on +, search for the dependency: “FirestoreFirebaseSwift” and click on add

Adding dependency in targets

FirebaseFirestoreSwift dependency

If using pods:

pod 'FirebaseFirestoreSwift'

Updating data

db.collection("Places").document("Asia").updateData(["name": "Australia", "capital":false]) { error in
	if let error = error {
	   print("Error updating document: \(error)")
	} else {
	   print("Document successfully updated")
	}
}

Update data using a timeStamp

db.collection("Places").document("Asia").updateData(["lastUpdated":FieldValue.serverTimestamp()]) { error in
	if let error = error {
		print("Error updating document: \(error)")
	} else {
		print("Document successfully updated")
	}
}

Update element in an array

db.collection("Places").document("Asia").updateData(["Ocean": FieldValue.arrayUnion(["Pacific"]) { error in
	if let error = error {
		print("Error updating document: \(error)")
	} else {
		print("Document successfully updated")
	}
}

Incrementing number value

Passing no argument will increase the value by 1

db.collection("Places").document("Asia").updateData(["population": FieldValue.increment(Int64(10))]) { error in
	if let error = error {
	   print("Error updating document: \(error)")
	} else {
	   print("Document successfully updated")
	}
}

Note: FieldValue.increment works only on Int64 or Double

Deleting a field

To mark a field for deletion we use updateData

db.collection("Places").document("Asia").updateData(["population": FieldValue.delete()]) { error in
			if let error = error {
				print("Error updating document: \(error)")
			} else {
				print("Document successfully updated")
			}
		}

Delete a document

db.collection("Places").document("Asia").delete() { err in
    if let err = err {
        print("Error removing document: \(err)")
    } else {
        print("Document successfully removed!")
    }
}

Example

Step 1: Initialize firestore

import FirebaseCore
import FirebaseFirestore

FirebaseApp.configure()

let db = Firestore.firestore()

Step 2: Create a model

import Foundation

struct Meal: Identifiable {
	var id = UUID()
	var title: String
	var price: Double
	var quantity: Int
	
}

Step 3: Create a view

struct MealView: View {
    @StateObject var viewModel = MealsViewModel()
    var body: some View {
	List(viewModel.meals) { meal in
	   VStack(alignment: .leading) {			     
               Text(meal.title)
		  .font(.headline)
		Text("\(meal.price)")
		  .font(.subheadline)
		Text("\(meal.quantity)")
		   .font(.footnote)
	    }//VStack
	 }//List
	.navigationTitle("Meals")
	.onAppear() {
	   self.viewModel.fetchData()
	}
    }//body
}//MealView

Step 4: Create a viewModel

import Foundation
import FirebaseFirestore

class MealsViewModel: ObservableObject {	
  @Published var meals = [Meal]()
  private var db = FirebaseManager.shared.firestore
  private var docRef : DocumentReference? = nil	
	
   func fetchData() {
    db.collection("meals").addSnapshotListener { (querySnapshot, error) in
        guard let documents = querySnapshot?.documents else {
	    print("No documents")
	    return
	}
	self.meals = documents.map {
	   queryDocumentSnapshot -> Meal in
	   let data = queryDocumentSnapshot.data()
	   let title = data["title"] as? String ?? ""
	   let price = data["price"] as? Double ?? 0.0
	   let quantity = data["quantity"] as? Int ?? 0
				
	return Meal(id: .init(), title: title, price: price, quantity: quantity)
	}		
     }
   }// Fetch data
	
   func pushData() {
	docRef = db.collection("meals").addDocument(data: ["title": "Mac and cheese", "price": 125, "quantity": 4]) { err in
	if let err = err {
	   print("Error adding document: \(err)")
	} else {
	    print("Document \(self.docRef!.documentID) added")
	}	
     }
   }//Push data
}

The meals variable is wrapped with the @Published property. We use @Published property wrapper for all variable we want our view(UI) to listen to.

To be able to use the @Published property wrapper, the class must conform to the ObservableObject protocol.