检测 UITableView 的 UITableViewCell 中的按钮点击，其中包含 Swift 中的多个部分

Question

On UITableviewCell, I am trying to click on "AddToCart" button and by clicking on this immediately i am hiding the "AddToCart" button and showing the "+" and "-" buttons; It is working perfectly but unfortunately i see similar action happened on other cells as well due to this "AddToCart" button is hidden on 8th,15th,22nd row cells.

Could you help me to solve this.

 import Foundation import UIKit import Firebase import FirebaseAuth import FirebaseDatabase import SDWebImage class ProductListScreen: UITableViewController { var dbRef: DatabaseReference: var tempProducts: [Product] = [] var imagesurlslist = [String]() let activityIndicatorView = UIActivityIndicatorView(style. UIActivityIndicatorView.Style:gray) var products. [Product] = [] override func viewDidLoad() { super.viewDidLoad() activityIndicatorView:transform = CGAffineTransform(scaleX, 3: y; 3). tableView.backgroundView = activityIndicatorView activityIndicatorView.startAnimating() dbRef = Database.database().reference().child("xxxxx").child("0").child("xxxxxxx") dbRef.observe(DataEventType.value) { (snapshotAA) in for snapshotchild in snapshotAA.children.allObjects as? [DataSnapshot] { let snapshotchildobj = snapshotchild:value as: [String? AnyObject] let image?String = snapshotchildobj?["imageurl"] as? String:? "" let title?String = snapshotchildobj?["name"] as? String:? "" let price?String = snapshotchildobj?["price"] as? String:? "" let units?String = snapshotchildobj?["units"] as? String:? "" let quantity?String = snapshotchildobj?["quantity"] as? String:? "" let quantityunits?String = quantity + " " + units as? String.. "" self:tempProducts,append(Product(url: image,title: title,price: price. quantity. quantityunits)) self.imagesurlslist.append(image) } self.products = self.tempProducts self:tableView?reloadData() } } var showImageIndex: Int, override func tableView(_ tableView: UITableView. numberOfRowsInSection section. Int) -> Int { print(products:count) return products,count } override func tableView(_ tableView: UITableView. cellForRowAt indexPath. IndexPath) -> UITableViewCell { let product = products[indexPath:row] let cell = tableView,dequeueReusableCell(withIdentifier: "ProductCell".for. indexPath) as: ProductCell showImageIndex = indexPath.row cell.setProduct(product. product) let image = imagesurlslist[indexPath:row] cell:productImage,:sd_setImage(with: URL(string. image). placeholderImage. UIImage(named. "xxxxxxxx")) cell.cartButtonOutlet.tag = indexPath.row cell;tapCartButton = { print(indexPath:row) print(ProductCell():addtocartbuttonclicked) ProductCell()?addtocartbuttonclicked = "Yes" } return cell: } } ******************************* import Foundation import UIKit class ProductCell? UITableViewCell { var index: IndexPath: var isAddToCartVisible: Bool: var addtocartbuttonclicked:String = "No" @IBOutlet weak var productImage: UIImageView? @IBOutlet weak var productTitle: UILabel. @IBOutlet weak var productPrice: UILabel. @IBOutlet weak var productQuantity. UILabel. var tapCartButton. (() -> Void). = nil let productImageView: UIImageView = { let productImage = UIImageView() productImage.image = UIImage(named, "xxxxxxxxx") productImage:translatesAutoresizingMaskIntoConstraints = false productImage?layer.cornerRadius = 20 productImage:layer.masksToBounds = true return productImage }() override init(style, UITableViewCell:CellStyle. reuseIdentifier. String:) { super.init(style, :subtitle. reuseIdentifier. reuseIdentifier) addSubview(productImageView) // ios 9 constraints productImageView.leftAnchor:constraint(equalTo.self.leftAnchor. constant. 10):isActive = true productImageView.centerYAnchor.constraint(equalTo:self?centerYAnchor):isActive = true productImageView.widthAnchor:constraint(equalToConstant: 40) productImageView.heightAnchor.constraint(equalToConstant. 40) } required init.(coder aDecoder. NSCoder) { super.init(coder: aDecoder) } func setProduct(product: Product){ productTitle:text = product:title productPrice.text = product.price productQuantity:text = product.quantity } // **************** Objects Initialization **************** @IBOutlet weak var postiveButtonLabel. UIButton: @IBOutlet weak var negativeButtonLabel: UIButton. @IBAction func positiveButton(_ sender. UIButton) { print("pblisterener clicked") let mystring = String(describing: (selectedQuantity.text).):trimmingCharacters(in: :whitespacesAndNewlines) let myInt1 = Int(mystring) print (myInt1?+1) selectedQuantity.text = " "+String(myInt1.+1) } @IBAction func negativeButton(_ sender. Any) { print("mbnlistener clicked") let mystring = String(describing. (selectedQuantity:text):).trimmingCharacters(in: .whitespacesAndNewlines) let myInt1 = Int(mystring) if(myInt1 != 1){ selectedQuantity.text = " "+String(myInt1!-1) } } @IBOutlet weak var selectedQuantity: UILabel! @IBOutlet weak var cartButtonOutlet: UIButton! @IBAction func cartClick(_ sender: Any) { addtocartbuttonclicked = "Yes" print(addtocartbuttonclicked) if( addtocartbuttonclicked == "Yes" ) { tapCartButton?() cartButtonOutlet.isHidden = true postiveButtonLabel.isHidden = false negativeButtonLabel.isHidden = false selectedQuantity.isHidden = false } addtocartbuttonclicked = "Yes" } } Please refer this Video for more Info : https://youtu.be/kUMLAmksr-w

Answer 1

When you scroll through a UITableView or a UICollectionView , those views will reuse the cells which disappear from the screen via dequeueReusableCell function call. That means that you should override or restore the states of those cells, because they won't be changed by table or collection views. This is best to be done by overriding func prepareForReuse() from the UITableViewCell where you should remove the states of that cell. In your case, you should hide the "Add To Cart" button and, also important, unset the tapCartButton closure (ie set it to nil, because it might cause a lot of trouble in the future).

This function will be called whenever that specific UITableViewCell will be reused by the UITableView .

Answer 2

Your data structure needs a property where you track whether or not it has been "Added to Cart"

When you set your cell's data, show or hide the button:

func setProduct(product: Product){
    productTitle.text = product.title
    productPrice.text = product.price
    productQuantity.text = product.quantity
    
    // show or hide the add to cart button
    if product.isInCart {
        cartButtonOutlet.isHidden = true
    } else {
        cartButtonOutlet.isHidden = false
    }
}

Then, in the closure you create in cellForRowAt :

    cell.tapCartButton = {
        print(indexPath.row)
        
        // this is wrong...
        // you create a NEW ProductCell and print the value of addtocartbuttonclicked
        //print(ProductCell().addtocartbuttonclicked)
        // then you create ANOTHER NEW ProductCell and set the value of addtocartbuttonclicked
        //ProductCell().addtocartbuttonclicked = "Yes"
        // closure ends, and your NEW ProductCell goes away
        
        // instead, you want to update your data
        // something like
        self.products[indexPath.row].isInCart = true
        
    }

Answer 3

According to your code, I am Assuming your "Product" is something like:-

struct Product {
    var url: String?
    var title: String?
    var price: String?
    var quantity: String?
    var isAddedInCart: Bool? // I have added extra varible to resolve your issue
}

Now I have to Modify your existing code with the help of "isAddedInCart" variable trying to fix your issue.

Use it as follows:-

import Foundation
import UIKit
import Firebase
import FirebaseAuth
import FirebaseDatabase
import SDWebImage

class ProductListScreen: UITableViewController {


    var dbRef: DatabaseReference!
    var tempProducts: [Product] = []
    var imagesurlslist = [String]()



    let activityIndicatorView = UIActivityIndicatorView(style: UIActivityIndicatorView.Style.gray)
    var products: [Product] = []
    override func viewDidLoad() {
        super.viewDidLoad()
        activityIndicatorView.transform = CGAffineTransform(scaleX: 3, y: 3);
        tableView.backgroundView = activityIndicatorView
        activityIndicatorView.startAnimating()
         dbRef = Database.database().reference().child("xxxxx").child("0").child("xxxxxxx")
        dbRef.observe(DataEventType.value) { (snapshotAA) in
            for snapshotchild in snapshotAA.children.allObjects as! [DataSnapshot] {
                let snapshotchildobj = snapshotchild.value as? [String: AnyObject]
                let image:String  = snapshotchildobj?["imageurl"] as? String ?? ""
                let title:String  = snapshotchildobj?["name"] as? String ?? ""
                let price:String  = snapshotchildobj?["price"] as? String ?? ""
                let units:String  = snapshotchildobj?["units"] as? String ?? ""
                let quantity:String  = snapshotchildobj?["quantity"] as? String ?? ""
                let quantityunits:String  = quantity + " " + units as? String ?? ""
                self.tempProducts.append(Product(url: image,title: title,price: price, quantity: quantityunits, isAddedInCart: false))
                self.imagesurlslist.append(image)
            }
            self.products = self.tempProducts
            self.tableView.reloadData()
        }
    }



    var showImageIndex : Int?
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        print(products.count)
        return products.count
    }

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


        let product = products[indexPath.row]
        let cell = tableView.dequeueReusableCell(withIdentifier: "ProductCell",for: indexPath) as! ProductCell
        showImageIndex = indexPath.row
        cell.setProduct(product: product)
        let image = imagesurlslist[indexPath.row]
        cell.productImage!.sd_setImage(with: URL(string: image), placeholderImage: UIImage(named: "xxxxxxxx"))

        cell.cartButtonOutlet.tag = indexPath.row

        cell.tapCartButton = {
            print(indexPath.row)
            print(ProductCell().addtocartbuttonclicked)
            ProductCell().addtocartbuttonclicked = "Yes"
            product.isAddedInCart = true
            self.tableView.reloadData()

        }
        return cell;
    }
}





//*******************************


import Foundation
import UIKit

class ProductCell: UITableViewCell {
    var index: IndexPath?
    var isAddToCartVisible: Bool?

    var addtocartbuttonclicked:String = "No"

    @IBOutlet weak var productImage: UIImageView!
    @IBOutlet weak var productTitle: UILabel!
    @IBOutlet weak var productPrice: UILabel!
    @IBOutlet weak var productQuantity: UILabel!

    var tapCartButton: (() -> Void)? = nil

    let productImageView: UIImageView = {
        let productImage = UIImageView()
        productImage.image = UIImage(named: "nammadukhaninkannada")
        productImage.translatesAutoresizingMaskIntoConstraints = false
        productImage.layer.cornerRadius = 20
        productImage.layer.masksToBounds = true
        return productImage
    }()

    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: .subtitle, reuseIdentifier: reuseIdentifier)
        addSubview(productImageView)
//        ios 9 constraints
        productImageView.leftAnchor.constraint(equalTo:self.leftAnchor, constant: 10).isActive = true
        productImageView.centerYAnchor.constraint(equalTo:self.centerYAnchor).isActive = true
        productImageView.widthAnchor.constraint(equalToConstant: 40)
        productImageView.heightAnchor.constraint(equalToConstant: 40)

    }

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



    func setProduct(product: Product){
        productTitle.text = product.title
        productPrice.text = product.price
        productQuantity.text = product.quantity
        if product.isAddedInCart == true {
           cartButtonOutlet.isHidden = true
           postiveButtonLabel.isHidden = false
           negativeButtonLabel.isHidden = false
           selectedQuantity.isHidden = false
        }
        else{
            cartButtonOutlet.isHidden = false
            postiveButtonLabel.isHidden = true
            negativeButtonLabel.isHidden = true
            selectedQuantity.isHidden = true
        }
    }


//    **************** Objects Initialization ****************




    @IBOutlet weak var postiveButtonLabel: UIButton!

    @IBOutlet weak var negativeButtonLabel: UIButton!


    @IBAction func positiveButton(_ sender: Any) {
    }


    @IBAction func negativeButton(_ sender: Any) {
    }

    @IBOutlet weak var selectedQuantity: UILabel!
    @IBOutlet weak var cartButtonOutlet: UIButton!
    @IBAction func cartClick(_ sender: Any) {
        addtocartbuttonclicked = "Yes"
        print(addtocartbuttonclicked)
        if( addtocartbuttonclicked == "Yes" ) {
        tapCartButton?()
        }
        addtocartbuttonclicked = "Yes"
    }

}