Question

我正在使用Swift 3.1，我的一个viewcontrollers中有一个表。当用户通过向左滑动并按下红色删除按钮删除表中的一个项目时，我想要弹出警报消息并说出一些内容。当我向左滑动以从UITableView表中删除某些内容时，下面的代码由于某种原因没有被触发。请参阅下面的10行左右，我用“CODE HERE”标记我的尝试。有什么方法可以在删除某些内容时触发此代码吗？

import UIKit

class CheckoutViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

@IBOutlet var table: UITableView!
@IBOutlet weak var checkoutButton: UIButton!
@IBOutlet weak var priceLabel: UILabel!

var items: [String] = []

internal func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    return items.count

}


// CODE HERE

func table(table: UITableView!, canEditRowAtIndexPath indexPath: NSIndexPath!) -> Bool {
    return true
}

func table(tableView: UITableView!, commitEditingStyle editingStyle:   UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath!) {
    let alertController = UIAlertController(title: "Sample Title", message: "Sample message", preferredStyle: .alert)
    let defaultAction = UIAlertAction(title: "Ok", style: .default, handler: nil)
    alertController.addAction(defaultAction)
    present(alertController, animated: true, completion: nil)
}

// CODE HERE    


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

    let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "Cell")

    cell.textLabel?.numberOfLines = 16
    cell.textLabel?.font = cell.textLabel?.font.withSize(10)
    cell.textLabel?.text = items[indexPath.row]

    return cell


}


override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.


}


override func viewDidAppear(_ animated: Bool) {
    priceLabel.text = String(format: "%.2f", totalPrice)
    let itemsObject = UserDefaults.standard.object(forKey: "items")


    if let tempItems = itemsObject as? [String] {

        items = tempItems

    }

    table.reloadData()
}

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

    if editingStyle == UITableViewCellEditingStyle.delete {

        items.remove(at: indexPath.row)

        table.reloadData()

        UserDefaults.standard.set(items, forKey: "items")

    }

}


@IBAction func checkoutClicked(_ sender: Any) {
    priceLabel.text = String(format: "%.2f", totalPrice)
    items.removeAll()
    table.reloadData()
    totalPrice = 0
    priceLabel.text = String(format: "%.2f", totalPrice)
    UserDefaults.standard.set(items, forKey: "items")
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

Answer 1

您在commit方法中尝试了两次。一个签名错误，一个签名正确。您对警报的使用是错误的。您确实需要清理代码并删除所有错误的方法。然后将所需的功能放入正确的方法中。

为什么你在这么多方法参数上拥有所有那些不必要的!运算符？

Answer 2

您应该在

中显示提醒

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

    if editingStyle == UITableViewCellEditingStyle.delete {

        items.remove(at: indexPath.row)

        table.reloadData()

        UserDefaults.standard.set(items, forKey: "items")

    }

}

完整代码：

import UIKit

class CheckoutViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

    @IBOutlet var table: UITableView!
    @IBOutlet weak var checkoutButton: UIButton!
    @IBOutlet weak var priceLabel: UILabel!

    var items: [String] = []

    internal func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        return items.count

    }

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

        let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: "Cell")

        cell.textLabel?.numberOfLines = 16
        cell.textLabel?.font = cell.textLabel?.font.withSize(10)
        cell.textLabel?.text = items[indexPath.row]

        return cell


    }


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.


    }


    override func viewDidAppear(_ animated: Bool) {
        priceLabel.text = String(format: "%.2f", totalPrice)
        let itemsObject = UserDefaults.standard.object(forKey: "items")


        if let tempItems = itemsObject as? [String] {

            items = tempItems

        }

        table.reloadData()
    }

    func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        return true
    }

    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

        if editingStyle == UITableViewCellEditingStyle.delete {

            items.remove(at: indexPath.row)

            table.reloadData()

            UserDefaults.standard.set(items, forKey: "items")

            let alertController = UIAlertController(title: "Sample Title", message: "Sample message", preferredStyle: .alert)
            let defaultAction = UIAlertAction(title: "Ok", style: .default, handler: nil)
            alertController.addAction(defaultAction)
            present(alertController, animated: true, completion: nil)

        }

    }


    @IBAction func checkoutClicked(_ sender: Any) {
        priceLabel.text = String(format: "%.2f", totalPrice)
        items.removeAll()
        table.reloadData()
        totalPrice = 0
        priceLabel.text = String(format: "%.2f", totalPrice)
        UserDefaults.standard.set(items, forKey: "items")
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

在Swift中，如何从UITableView中删除项目时触发事件？

2 个答案: