ios - 在没有 Segues 的 ViewController 之间传输数据 - Swift

Question

我注册了 viewController(VC)。一旦用户提交了他的注册详细信息，我的远程服务器就会响应“registration_success”。收到此消息后，我可以提供一个新的 VC，请求用户检查他们的电子邮件以验证他们的电子邮件地址。我能够展示新的 View Controller ，但无法将用户的电子邮件地址转移到新的 VC。我的代码如下:

     guard
          let registeredEmail = myArray["email"] as? String else{
          print("cannot find email address")
          return
          }

          let verifyEmailVC = self.storyboard?.instantiateViewController(withIdentifier: "emailConfirmVC") as! VerifyEmailViewController
          print("registeredEmail: \(registeredEmail)")
          verifyEmailVC.emailToVerify.text! = registeredEmail
          self.present(verifyEmailVC, animated: true, completion: nil)

VerifyEmailViewController 类:

    class VerifyEmailViewController: UIViewController {

    @IBOutlet var emailToVerify: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

    }

}

控制台:

 jsonObject: {
email = "tran123@gmail.com";
firstname = Wang;
lastname = tran;
message = "registration_success";
status = 200;
userId = 53;
}
message: registration_success
registeredEmail: tran123@gmail.com

我收到以下错误:

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

行内:verifyEmailVC.emailToVerify.text! =注册邮箱

Answer 1

VerifyViewController 中的标签为 nil，您正在尝试为该标签设置值。尝试像这样将字符串传递给您的 Controller

let verifyEmailVC = self.storyboard?.instantiateViewController(withIdentifier: "emailConfirmVC") as! VerifyEmailViewController
print("registeredEmail: \(registeredEmail)")
verifyEmailVC.email = registeredEmail
self.present(verifyEmailVC, animated: true, completion: nil)


class VerifyEmailViewController: UIViewController {

@IBOutlet var emailToVerify: UILabel!
var email: String?

override func viewDidLoad() {
    super.viewDidLoad()
    emailToVerify.text = email
}