How to access values in one class from another? Swift 4 - ios

Question

I have an app where when a user taps a cell from a TableView representing a group of images, he is taken to another tableView where all the images within that group should be shown. However I am unsure of how to do this.
I have currently have extracted at the beginning the info necessary to make a reference and get all the data, which is in an array of objects. However how can I access these values from another class?
DataModel:
struct UserImage {
var userID: String
var image: UIImage
var postNum: String
}
I am creating an array of this as shown bellow, in a P1TableVC:
let arrayOfUserImageData = [UserImage]()
The function which retrieves and store the data looks as follows:
func fetchAllUserFristImage() {
print("Description: calling of fetchAllUserFristImage()")
Database.database().reference().child("Posts").observe(.childAdded, with: {(snapshot) in
if snapshot.value as? [String: AnyObject] != nil {
let user = snapshot.key
print("Description: calling of snapshot.value is not nil ")
self.databaseRef = Database.database().reference()
let usersPostRef2 = self.databaseRef.child("Posts").child(user)
usersPostRef2.observe(.value, with: {(postXSnapshots) in
if let postDictionary2 = postXSnapshots.value as? [String:AnyObject] {
for (p) in postDictionary2 {
if let posts = p.value as? [String:AnyObject] {
print("Description: posts has value of: \(posts)")
//to get back to where i was delete the below for i
for (i) in posts {
if let imageUrlString = i.value as? [String:AnyObject], let postUrl = imageUrlString["image1"] as? String {
print("Description: inside the if let imageUrlString = i.value ")
self.feedArray.append(Post(fetchedImageURL: postUrl))
if let imageUrl = URL(string: postUrl), let imageDataL = try? Data(contentsOf: imageUrl), let image = UIImage(data: imageDataL) {
print("Description: inside the if let imageUrl = URL(string: postUrl)")
print("Description: img url's of posts: \(imageUrl)")
self.tableData.append(UserImage(userID: user, image: image, postNum: p.key))
self.tableView.reloadData()
} else {print("this user had no posts, was nil")}
}
}
}
}
}
})
//below shud stay same
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
})
}

Answer 1

In didSelectItem method fetch the selected data from tableData based on indexPath.row and pass this data to next controller (make a variable in next controller and before pushing/presenting assign the fetched data to that variable).
didSelectItem : Fetch the selected data - let data = tableData[indexPath.row]
Assign it to next controller's variable -
let vc = nextVC()
vc.fetchedData = data
push/present vc

Answer 2

Or you may probably use Singleton
For instance: just create class Model
class Model {
static let sharedInstance = Model()
var tableVC: P1TableVC!
}
Then inside of your VC in viewDidLoad
class P1TableVC: UIViewController {
override func viewDidLoad() {
Model.sharedInstance.tableVC = self
}
}
Then you can use your class everywhere you want
Model.sharedInstance.tableVC.arrayOfUserImageData
Or you can create variable for all your data
class Model {
static let sharedInstance = Model()
var data: [UserImage]()
}
And then use data not VC
Model.sharedInstance.data