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Enrique Espinosa
Asked: 2020-05-21 08:22:18 +0800 CST 2020-05-21 08:22:18 +0800 CST

Send arguments or parameters from a #selector in Swift 4?

  • 772

I have a problem, I created some buttons in a cell of a UITableView, my cell has a class where the IBoutlets of my labels and my buttons are created, and in the cellForRowAt method I assign my cell as follows:

let cell = tableview.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! PostViewCell

the problem I have is that when I want to use one of the buttons that I create from that cell I do the following:

cell.btnLike.addTarget(self, action: #selector(addLike(idPost:idLike:)), for: .touchUpInside)

I do it this way to be able to access a function called addLike that receives two parameters:

@objc func addLike(idPost: Int, idLike: Int){
        print("Like")
    }

As I am making use of a #selector to my function, I added the @objc so that it can be used within that selector, now my problem is that I don't know how I can pass the two parameters, that is, something similar to this:

#selector(addLike(idPost: 1, idUserPost: 2))

If I do it this way, I get an error, my question is, how can I pass two parameters from the #selector.

swift

2 Answers

  1. Best Answer

    Parameters cannot be sent according to Apple documentation. The best way to work is with Protocolos. I leave you a simple example:

    PostViewCell.swift

    import UIKit

protocol ProtocolPostViewCell {
    func onClick(idPost: Int, idUserPost: Int)
}

class PostViewCell: UITableViewCell {

    @IBOutlet weak var tuButton: UIButton!

    var postViewDelegate: ProtocolPostViewCell? = nil
    var idPost: Int = 0
    var idUserPost: Int = 0

    @IBAction func tuFuncion(_ sender: Any) {
        postViewDelegate?.onClick(idPost: self.idPost, idUserPost: self.idUserPost)
    }
}

    TableViewController.swift

    import UIKit

class TuTableViewController: UITableViewController, ProtocolPostViewCell {
     var idPost: [Int] = //Los valores los obtienes de algún lado
     var idUserPost: [Int] = //Los valores los obtienes de algún lado

    func onClick(idPost: Int, idUserPost: Int) {
        //Obtienes los valores del botón que hiciste click
        print(idPost)
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableview.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! PostViewCell
        cell.postViewDelegate = self //Asignas al delegate para que se active las función al hacer click
        cell.idPost = self.idPost[indexPath.row]//Asignas valores
        cell.idUserPost = self.idUserPost[indexPath.row]//Asignas valores
    }
}

    This way each button filawill have a unique identifier assigned to it.

    • 1

  2. Good morning, I recommend you use closures, taking the example of the person above, the code would be the following.

    PostViewCell.swift

    import UIKit


class PostViewCell: UITableViewCell {

    @IBOutlet weak var tuButton: UIButton!

    var actionButtonTapped : ((Int , Int) -> ())?
    var idPost: Int = 0
    var idUserPost: Int = 0

    @IBAction func tuFuncion(_ sender: Any) {
        guard let actionButtonTapped = actionButtonTapped else {return}
        actionButtonTapped(self.idPost , self.idUserPost)
    }
}

    TableViewController.swift

    import UIKit

class TuTableViewController: UITableViewController {
     var idPost: [Int] = //Los valores los obtienes de algún lado
     var idUserPost: [Int] = //Los valores los obtienes de algún lado

    func onClick(idPost: Int, idUserPost: Int) {
        //Obtienes los valores del botón que hiciste click
        print(idPost)
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableview.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! PostViewCell
        cell.idPost = self.idPost[indexPath.row]//Asignas valores
        cell.idUserPost = self.idUserPost[indexPath.row]//Asignas valores
        cell.actionButtonTapped = {[weak self] (idPost , idUserPost) in
           print(idPost, idUserPost)
}
    }
}

    consider that closure is the best solution for your case because you are only passing a function, usually I use the protocols when I use more functions in which I want to delegate the responsibility

    • 0