VoteController.swift

import UIKit
import Firebase

class VoteController: UIViewController {
    
    //MARK: Global Variables
    var ref: DatabaseReference?
    var songs = [Song]()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        //Check if user is signed into Firebase
        if let uid = Auth.auth().currentUser?.uid {
            ref = Database.database().reference()
        }
        fetchData {
            print(self.songs)
        }
        
    }
    
    func fetchData(completed: @escaping ()->()) {
        self.ref?.child("songs").observe(.childAdded, with: { (snapshot) in
            
            //Cast Firebase data snapshot as dictionary
            if let dictionary = snapshot.value as? [String: AnyObject] {
                let song = Song()
                var ratio: String?
                
                //Store each song's data into Song model
                song.name = dictionary["name"] as? String
                song.elo = dictionary["elo"] as? Int
                song.wins = dictionary["wins"] as? Int
                song.losses = dictionary["losses"] as? Int
                
                if song.losses! != 0 && song.wins! == 0 {
                    ratio = "0%"
                }
                
                if song.losses! == 0 && song.wins! == 0{
                    ratio = "n/a"
                }
                
                if song.losses! == 0 && song.wins! != 0 {
                    ratio = "100%"
                }
                
                if song.losses! != 0 && song.wins! != 0 {
                    let ratioCalculation = (Double(song.wins!)/((Double(song.wins!)) + (Double(song.losses!))) * 100)
                    let roundedRatioCalculation = Int(round(ratioCalculation))
                    ratio = "\(roundedRatioCalculation)%"
                }
                
                song.ratio = ratio
                
                //Add each song to songs array
                self.songs.append(song)
            }
            completed()
        })
    }
    
}