swift - 无法在 View Controller 之间传递数据

Question

我试图将ViewController中的字符串sendname传递给另一个 View Controller DatabaseTableViewController中的字符串变量finalName.这是我在 ViewController 中的代码:

                    self.sendname = self.name.text!
                    let vc = DatabaseTableViewController()
                    print("sending: \(self.sendname)")
                    vc.finalName = self.sendname
                    self.navigationController?.pushViewController(vc, animated: true)
                    let next = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DatabaseTableViewController") as! DatabaseTableViewController
                    self.present(next, animated: true, completion: nil)

以及我在DatabaseTableViewController中的viewDidLoad中的变量:

class DatabaseTableViewController: UIViewController {

    var finalName: String? = nil

我的代码正确打印sending: Satya，但是当我在DatabaseTableViewController中打印finalName的值时，它仍然给我无。我该怎么办？

谢谢，萨蒂亚

Answer 1

您将值分配给未呈现的实例

                let vc = DatabaseTableViewController()
                print("sending: \(self.sendname)")
                vc.finalName = self.sendname
                self.navigationController?.pushViewController(vc, animated: true)
                let next = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DatabaseTableViewController") as! DatabaseTableViewController

您预设了next，但未为其分配数据

 self.present(next, animated: true, completion: nil)

<小时/>

注意您的 vc 是否存在于 Storyboard 中，然后实例化

 let next = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DatabaseTableViewController") as! DatabaseTableViewController

如果以编程方式则使用

 let vc = DatabaseTableViewController()

所以尝试一下

    let vc= UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DatabaseTableViewController") as! DatabaseTableViewController
   print("sending: \(self.sendname)")
   vc.finalName = self.sendname
   self.navigationController?.pushViewController(vc, animated: true)