swift中的UITextfield致命错误

Question

在我的 swift 应用程序中，我正在使用解析。在解析登录注册字段详细信息时，我在文本字段中收到类似 "fatal error: unexpectedly found nil while unwrapping an Optional value" 之类的错误。请帮助我。我的代码如下。

//CLASS 1
class login: UIViewController{ 
  @IBAction func create_acc_but(sender: UIButton) { 
    createaccount.shared.create_account() 
   }
}
// CLASS 2

public class createaccount {

let login_obj:login = login()
class var shared: createaccount {
    struct Static {
        static let instance: createaccount = createaccount()
    }
    return Static.instance
 }

func create_account() {


    var user = PFUser()

    user.username = login_obj.username_txtfd.text //receiving error in this line.
    user.email =  login_obj.email_txtfd.text
    user.password = login_obj.passwd_txtfd.text

    user.signUpInBackgroundWithBlock {
        (succeeded: Bool!, error: NSError!) -> Void in
        if error == nil {
            // Hooray! Let them use the app now.
        } else {
            let errorString = error.userInfo // error.userInfo["error"] as NSString
            println(errorString)
            // Show the errorString somewhere and let the user try again.
        }
    }
  }
 }

Answer 1

这完全是关于可选值的包装和展开。此错误是因为您试图解开可选值。确保你的属性必须声明为可选，像这样

@IBOutlet var txtNumber1:UITextField!

你可以像这样访问值

var a:Int! = txtNumber1.text.toInt()

有关可选的更多信息，请访问此链接：http://www.appcoda.com/beginners-guide-optionals-swift/

这绝对会帮助你