Swift委托和协议方法未在iOS中调用

Question

I have parsing the JSON values in UITableView using MVC pattern, For that, I have created a separate UITableView swift class, Model class, and UIViewController class as well.

I can able to parse the JSON values into the table view. But the problem is I can't able to pass the selected tableView cell values to my controller using the delegate method

Here my code is

UIVIewController :

class ViewController: UIViewController,contactSelectionDelegate {
var contactArray = [Address]()
@IBOutlet weak var userTable: UserTable!
let user = UserTable()


override func viewDidLoad() {
    super.viewDidLoad()

    user.userdelegate? = self
    if Connectivity.isConnectedToInternet() {
        print("Yes! Network connection is available")
        APIManager.sharedInstance.fetchUserDetails(urlString: FETCH_USER_DETAIL_URL, userCount: ["offset":1]) { connectionResult in

            switch connectionResult {
            case .success(let data):
                do {
                    self.contactArray = try JSONDecoder().decode([Address].self, from: data)

                    print(self.contactArray.count)
                    print(self.contactArray[0].Name)

                    DispatchQueue.main.async {
                        print(self.contactArray)
                        self.userTable.dataSourceArray=self.contactArray
                        self.userTable.reloadData()
                    }
                }
                catch let errorValue {
                    print(errorValue)
                }
            case .failure(let error):
                print(error)
            }
        }
    }
    else{
        print("No network connection")
    }
}

func selectedUserContact(name: String, email: String, phone: String) {
    print("Delegate Called")
    let userdetailVC = storyboard?.instantiateViewController(withIdentifier: "UserContactDetailPage") as! UserContactDetailPage
    userdetailVC.name = name
    userdetailVC.email = email
    userdetailVC.phone = phone
    self.navigationController?.pushViewController(userdetailVC, animated: true)
} }

UITableView :

protocol contactSelectionDelegate: class{
func selectedUserContact(name: String ,email: String ,phone: String)
}

class UserTable: UITableView ,UITableViewDelegate ,UITableViewDataSource  {


var dataSourceArray  =   [Address]()
weak var userdelegate: contactSelectionDelegate?

override init(frame: CGRect, style: UITableViewStyle) {
    super.init(frame: frame, style: style)
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override func awakeFromNib() {
    super.awakeFromNib()
    self.delegate=self
    self.dataSource=self
}

func numberOfSections(in tableView: UITableView) -> Int {
    return 1;
}

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.dataSourceArray.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell:UserCell   =   tableView.dequeueReusableCell(withIdentifier: "UserCell", for: indexPath) as! UserCell
    if self.dataSourceArray.count>0 {
        let myUser  =   self.dataSourceArray[indexPath.row]
        cell.nameLbl.text  =   myUser.Name
        cell.emailLbl.text  =   myUser.Email
        cell.phoneLbl.text =   myUser.Phone
    }
    return cell
}

func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 200
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let myUser  =   self.dataSourceArray[indexPath.row]
    print(myUser.Name)
    print(myUser.Email)
    print(myUser.Phone)
     userdelegate?.selectedUserContact(name: myUser.Name, email: myUser.Email, phone: myUser.Phone)
}}

Here when I click table on the tableView cell didSelectRowAtIndexPath method called but selectedUserContact not getting called.

Answer 1

You've misunderstood the purpose of delegating here. The idea is that your table view is only responsible for drawing a table, it shouldn't be responsible for maintaining any of the data that it's displaying. This allows you to cleanly design your code using the Model-View-Controller (MVC) paradigm. Delegation allows your controllers to pass model information to the views without breaking MVC.

In your example: Address is the model, the table view is the view, and your view controller is the controller. So you want your controller to conform to the table view's delegate/data source protocols so that it can feed the data to it correctly.

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
    var contactArray = [Address]()
    @IBOutlet weak var userTable: UserTable!

    override func viewDidLoad() {
        super.viewDidLoad()

        if Connectivity.isConnectedToInternet() {
            print("Yes! Network connection is available")
            APIManager.sharedInstance.fetchUserDetails(urlString: FETCH_USER_DETAIL_URL, userCount: ["offset":1]) { connectionResult in

                switch connectionResult {
                case .success(let data):
                    do {
                        self.contactArray = try JSONDecoder().decode([Address].self, from: data)

                        print(self.contactArray.count)
                        print(self.contactArray[0].Name)

                        DispatchQueue.main.async {
                            print(self.contactArray)
                            self.userTable.reloadData()
                        }
                    }
                    catch let errorValue {
                        print(errorValue)
                    }
                case .failure(let error):
                    print(error)
                }
            }
        }
        else{
            print("No network connection")
        }
    }

    // MARK: - UITableViewDataSource

    func numberOfSections(in tableView: UITableView) -> Int {
        return 1;
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.contactArray.count
    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell: UserCell = tableView.dequeueReusableCell(withIdentifier: "UserCell", for: indexPath) as! UserCell
        let myUser = self.contactArray[indexPath.row]
        cell.nameLbl.text = myUser.Name
        cell.emailLbl.text = myUser.Email
        cell.phoneLbl.text = myUser.Phone
        return cell
    }

    // MARK: - UITableViewDelegate

    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 200
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let myUser = self.contactArray[indexPath.row]
        print(myUser.Name)
        print(myUser.Email)
        print(myUser.Phone)
        selectedUserContact(name: myUser.Name, email: myUser.Email, phone: myUser.Phone)
    }

    // MARK: -

    func selectedUserContact(name: String, email: String, phone: String) {
        print("Delegate Called")
        let userdetailVC = storyboard?.instantiateViewController(withIdentifier: "UserContactDetailPage") as! UserContactDetailPage
        userdetailVC.name = name
        userdetailVC.email = email
        userdetailVC.phone = phone
        self.navigationController?.pushViewController(userdetailVC, animated: true)
    }
}

EDIT: I just want to add that you need to make sure in your storyboard that you set ViewController as the delegate and dataSource of the table view. Then you can remove all the code that you've written in the UserTable class. If anything you don't need it at all and your table view can be a simple UITableView . I almost never create subclasses of it, since you can normally do everything through the delegation and UITableViewCell subclasses.

Answer 2

According to this line, Your have a table view in the storyboard and taken outlet in viewcontroller.

@IBOutlet weak var userTable: UserTable!

So you don't need to do this like that:

let user = UserTable()

You have to give delegate like this:

userTable.userdelegate? = self

Answer 3

Looks like you're instantiating the table view from a storyboard, so you're not setting the delegate on the correct instance of UserTable (and the delegate method is never called because the delegate is nil).

In the view controller change

user.userdelegate? = self

to

userTable.userdelegate? = self

Answer 4

For mine it is working fine with the below scenario. Kindly check with that one.

UserTable

@objc protocol contactSelectionDelegate: class {
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
}

weak var userdelegate: contactSelectionDelegate?
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        delegate?.tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
}

ViewController

class ViewController: UIViewController {

}

extension ViewController: contactSelectionDelegate {
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    // YOU CAN GET THE ALL THE STUFFS WHICH IS USER SELECTED IN THE TABLE VIEW
    }
}