How to observe more levels from realtime-database Firebase? - ios

Question

My code do not add values from a while statement of a UIViewController to an Array of a UITableViewController.
This is for a getter function to allow me to see all childrens values under other childrens. Now I'm going to be more specific:
My database node is made of:
Cars -> 0, 1, 2, 3, ... -> Model, Price, ... -> String
As you can see, The number of childs is undefined, so I have to use this control method:
while let child = snapshotChildren.nextObject() as? DataSnapshot {
// Get code node key and save it to cars array
}
First of all, In a loading ViewController, I get code node keys of cars and save them to cars variable of type NSMutableArray of the TableViewController. Then I will do the same thing in the TableViewController to get all indexpath.row childrens value.
let rootRef = Database.database().reference()
let carconditionalRef = rootRef.child("Cars")
carconditionalRef.observe(.value) {(snap: DataSnapshot) in
//Get all the children from snapshot you got back from Firebase
let snapshotChildren = snap.children
//Loop over all children (code) in Firebase
while let child = snapshotChildren.nextObject() as? DataSnapshot {
// Get code node key and save it to cars array
let carvc = Cars_Table();
carvc.cars.add(child.key)
}
}
It results that with this code I still have empty NSMutableArray. How can I solve this?
Edit 1
I fixed that snippet to this:
import UIKit
import FirebaseDatabase
class Loading: UIViewController {
#IBOutlet weak var loading: UIActivityIndicatorView!
var mother: NSMutableArray = []
override func viewDidLoad() {
super.viewDidLoad()
start()
}
func start() {
loading.startAnimating()
if #available(iOS 10.0, *) {
Timer.scheduledTimer(withTimeInterval: 0.1, repeats: false) { (timer) in
//let's dance
self.loading.startAnimating()
//call data from database
let rootRef = Database.database().reference()
let conditionalRef = rootRef.child("Cars")
conditionalRef.observe(.value) {(snap: DataSnapshot) in
// Get all the children from snapshot you got back from Firebase
let snapshotChildren = snap.children
// Loop over all children (code) in Firebase
while let child = snapshotChildren.nextObject() as? DataSnapshot {
// Get code node key and save it to cars array
self.mother.add(child.key)
}
self.move()
self.loading.stopAnimating()
self.performSegue(withIdentifier: "loadingfinish", sender: nil)
}
}
} else {
// Fallback on earlier versions
}
}
func move() {
let vc = Cars_Table()
vc.cars = self.mother
}
}
Edit 2
I tried using the recursive method, but it did not work. So I tried one more time with the iterative method this time using the while statement.
Here my new function, this time directly in the Car_TableView.swift:
func loadData() {
//call data from database
let rootRef = Database.database().reference()
let conditionalRef = rootRef.child("Cars")
conditionalRef.observe(.value) {(snap: DataSnapshot) in
// Get all the children from snapshot you got back from Firebase
let snapshotChildren = snap.children
// Loop over all children (code) in Firebase
while let child = snapshotChildren.nextObject() as? DataSnapshot {
// Get code node key and save it to cars array
self.populateTable.append(child.key)
}
var counter = 0
while counter > -self.populateTable.count {
counter -= 1
let rootRef = Database.database().reference()
let userRef = rootRef.child("Cars").child("\(self.populateTable.count+counter)")
userRef.observeSingleEvent(of: .value, with: { snapshot in
let userDict = snapshot.value as! [String: Any]
let model1 = userDict["Model"] as! String
self.model.add(model1)
let detail1 = userDict["Detail"] as! String
self.detailpage.add(detail1)
let year1 = userDict["Year"] as! String
self.year.add(year1)
let carPrice1 = userDict["Price"] as! String
self.price.add(carPrice1)
let carimageURL1 = userDict["imageURL"] as! String
self.imagePathString.add(carimageURL1)
}) //end observeSingleEvent
}
}
}
When I go to do the while, the observeSingleEvent will be work, but it will repeat n^2 times. Why does this happen?
Edit 3
Since the problem seems to be changed since the start, I edited to give all the relevant details. So, the problem now is different and now are two:
When I load database I have n^2 repeated instruction
To see the table filled with database data, I have to touch the tab bar button to the next ViewController then touch the tab bar button to come back on Car_TableView.swift
For the first problem... onestly I have no idea why this happens 😅
For the second problem I thought to use SVProgressHUD to reload data but it doesn't work on loadData() function and if I try the Instance Method tableView.reloadData() it crashes.
variables are all NSMutableArray since that I have to load a lot of stuff that can change in the time
My viewDidLoad() function is very easy as you can see:
override func viewDidLoad() {
super.viewDidLoad()
loadData()
}
This is my Table view data source in our Car_TableView.swift:
override func numberOfSections(in tableView: UITableView) -> Int {
return populateTable.count
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return populateTable.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellIdentifier = "carTableCell"
let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier) as! Car_Cell
cell.carLabel?.text = "\(self.model[indexPath.row])"
cell.carSubtitle?.text = "Year: \(self.year[indexPath.row]) - Price: \(self.price[indexPath.row])$"
Alamofire.request("\(self.imagePathString[indexPath.row])").response { response in
guard let image = UIImage(data:response.data!) else {
// Handle error
return
}
let imageData = image.jpegData(compressionQuality: 1.0)
cell.carImage.contentMode = .scaleAspectFit
cell.carImage.image = UIImage(data : imageData!)
}
return cell
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ShowcarDetails" {
let myIndexPath = self.tableView.indexPathForSelectedRow!
//save detail page url in UserDefault
let SVDetail = self.detailpage[myIndexPath.row]
let SVDetaildefaults = UserDefaults.standard
SVDetaildefaults.set(SVDetail, forKey: "sv_detail")
SVDetaildefaults.synchronize()
_ = segue.destination
as! Car_Detail
}
}
//SET CELLS SIZE
override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
switch indexPath.row {
case 0,1,2,3,4:
return 100
default:
return 100
}
}
I also re-post the loadData() function because I simplified the operation in an only while statement:
func loadData() {
//call data from database
let rootRef = Database.database().reference()
let conditionalRef = rootRef.child("Cars")
conditionalRef.observe(.value) {(snap: DataSnapshot) in
// Get all the children from snapshot you got back from Firebase
let snapshotChildren = snap.children
// Loop over all children (code) in Firebase
while let child = snapshotChildren.nextObject() as? DataSnapshot {
// Get code node key and save it to cars array
self. populateTable.append(child.key)
let userRef = rootRef.child("Cars").child("\(child.key)")
userRef.observeSingleEvent(of: .value, with: { snapshot in
let userDict = snapshot.value as! [String: Any]
let address1 = userDict["Address"] as! String
self.address.add(address1)
let detail1 = userDict["Detail"] as! String
self.detailpage.add(detail1)
let carnumberOfRooms1 = userDict["numberOfRooms"] as! String
self.numberOfRooms.add(carnumberOfRooms1)
let carPrice1 = userDict["Price"] as! String
self.price.add(carPrice1)
let carimageURL1 = userDict["imageURL"] as! String
self.imagePathString.add(carimageURL1)
}) //end observeSingleEvent
} //end while
} //end snap
}//end func