ios - 在 Swift 中的 TableView 和另一个 ViewController 之间传递数据

Question

我试图在 tableView 中显示一个事件列表，当用户按下其中一个事件时，它将打开另一个 viewController，其中包含有关该特定选择的更多信息。

这是具有可以选择的选项的tableView:

import UIKit
import Firebase
import FirebaseAuth
import FirebaseDatabase

class NewsfeedViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

    var ref:DatabaseReference!,
        posts = [eventStruct]()
    @IBOutlet weak var tableview: UITableView!
    var propertStruct : (Any)? = nil


    override func viewDidLoad() {
        super.viewDidLoad()
        loadNews()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func loadNews() {
        ref = Database.database().reference()
        ref.child("events").queryOrderedByKey().observe(.childAdded, with: { (snapshot) in

            if let valueDictionary = snapshot.value as? [AnyHashable:String]
            {
                let title = valueDictionary["Title"]
                let location = valueDictionary["Location"]
                let date = valueDictionary["Date"]
                let description = valueDictionary["Description"]
                self.posts.insert(eventStruct(title: title, date: date, location: location, description: description), at: 0)
                self.tableview.reloadData()
            }
        })

    }

    /////////////////////////     Table View Content     \\\\\\\\\\\\\\\\\\\\\\\\\\
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

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

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
        let label1 = cell.viewWithTag(1) as! UILabel
        label1.text = posts[indexPath.row].title
        let label2 = cell.viewWithTag(2) as! UILabel
        label2.text = posts[indexPath.row].location
        let label3 = cell.viewWithTag(3) as! UILabel
        label3.text = posts[indexPath.row].date
        return cell
    }

    func prepareForSegue(segue: UIStoryboardSegue, sender: eventStruct) {
        let secondViewController = segue.destination as? EventViewController
        secondViewController?.data = sender
    }

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        performSegue(withIdentifier: "showDetails", sender: posts[indexPath.row])
    }
    /////////////////////////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
}

struct eventStruct {
    let title: String!
    let date: String!
    let location: String!
    let description: String!


}

这里是 DetailsViewController，它应该显示在前面的 tableView 中选择的不同选项的标题:

import UIKit

class EventViewController: UIViewController {

    var data: eventStruct?
    @IBOutlet weak var titleLabel: UILabel!


    override func viewDidLoad() {
        super.viewDidLoad()
        print (data?.title as Any)
        self.titleLabel.text = self.data?.title

        // Do any additional setup after loading the view.
    }

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


    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

问题在于，不是显示应该存储在结构变量中的标题，而是始终返回一个 nil 值。

有人可以告诉我我做错了什么吗？我已尝试遵循所有提出的建议，但没有任何效果。

Answer 1

您的 prepareForSegue 必须覆盖 UIViewController 方法，即

func prepare(for segue: UIStoryboardSegue, sender: Any?)

因此您在 NewsfeedViewController 中的方法应该是

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    let secondViewController = segue.destination as? EventViewController
    secondViewController?.data = sender as? eventStruct
}

添加一些错误检查也是个好主意