fetching images from firebase in swift 3 - uitableview

Question

I am using Firebase as a backend for my project.I need to display text and image from Firebase database in tableview. It displays only text in my tableview and shows error while retrieving image as "cannot convert value of type 'UIImage?' to expected argument type 'String'".Please anyone, who can correct me. My code is given below:
//App Delegate
import UIKit
import CoreData
import Firebase
import FirebaseDatabase
import FirebaseStorage
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
FIRApp.configure()
return true
}
//View Controller
import UIKit
import Firebase
import FirebaseDatabase
import FirebaseStorage
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
var ref: FIRDatabaseReference? = nil
var refHandle: UInt? = nil
var userList = [User]()
#IBOutlet var tblHome: UITableView!
let textCellIdentifier = "TextCell"
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
tblHome.delegate = self
tblHome.dataSource = self
self.ref = FIRDatabase.database().reference()
print("ref = ",ref)
fetchUsers()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print("userList is", userList.count)
return userList.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: textCellIdentifier, for: indexPath) as! HomeCell
cell.profname.text = userList[indexPath.row].imageName
if let url = URL.init(string: userList[indexPath.row].imageUrl) { // Error: cannot convert value of type 'UIImage?' to expected argument type 'String'
cell.profImage.image.downloadedFrom(url: url)
}
return cell
}
func fetchUsers() {
refHandle = ref?.child("Users").observe(.childAdded, with: { (snapshot) in
print("refHandle =", self.refHandle)
if let dictionary = snapshot.value as? [String: AnyObject] {
print("dictionary =", dictionary)
let user = User()
user.setValuesForKeys(dictionary)
self.userList.append(user)
print("userlist is", user)
DispatchQueue.main.async(execute: {
self.tblHome.reloadData()
})
}
})
}
}
extension UIImageView {
func downloadedFrom(url: URL, contentMode mode: UIViewContentMode = .scaleAspectFit) {
contentMode = mode
URLSession.shared.dataTask(with: url) { (data, response, error) in
guard let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
let mimeType = response?.mimeType, mimeType.hasPrefix("image"),
let data = data, error == nil,
let image = UIImage(data: data)
else { return }
DispatchQueue.main.async() { () -> Void in
self.image = image
}
}.resume()
}
// func downloadedFrom(link: String, contentMode mode: UIViewContentMode = .scaleAspectFit) {
// guard let url = URL(string: link) else { return }
// downloadedFrom(url: url, contentMode: mode)
// }
}
//Home Cell
import UIKit
class HomeCell: UITableViewCell {
#IBOutlet var profImage: UIImageView!
#IBOutlet var profname: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
}
//User
import UIKit
class User: NSObject {
var imageName: String?
var imageUrl: UIImage?
}

Answer 1

According to the documentation, URL() takes a String and you are passing a UIImage to it.
Inside your User class, imageUrl is of type UIImage? and you are passing it into the URL constructor even though it is expecting a String.
You can solve this by changing your User class to this:
class User: NSObject
{
var imageName: String?
var imageUrl: String? // pass this to the URL constructor
var image: UIImage? // this stores the actual image
}