如何从另一个类访问一个类中的值？ 斯威夫特4

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

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

Answer 2

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).

1. didSelectItem : Fetch the selected data - let data = tableData[indexPath.row]

2. Assign it to next controller's variable -

   let vc = nextVC() vc.fetchedData = data push/present vc