【发布时间】：2017-09-10 14:39:30
【问题描述】：
我正在尝试创建一个应用程序，并且我想在出现登录错误或用户忘记输入用户名和/或密码时显示警报。但是，我总是收到此警告：
警告：尝试在 谁的视野不在窗内 等级制度！
我已经尝试了在这里找到的其他解决方案，但我仍然无法修复它。这是我的代码：
func createAlert(title: String, message: String) {
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (action) in
self.dismiss(animated: true, completion: nil)
}))
self.present(alert, animated: true, completion: nil)
}
@IBAction func signInPressed(_ sender: Any) {
if usernameTextField.text == "" || passwordTextField.text == "" {
createAlert(title: "Error in form", message: "Please enter an email and password.")
} else {
var activityIndicator = UIActivityIndicatorView()
activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
activityIndicator.center = self.view.center
activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
view.addSubview(activityIndicator)
activityIndicator.startAnimating()
UIApplication.shared.beginIgnoringInteractionEvents()
PFUser.logInWithUsername(inBackground: usernameTextField.text!, password: passwordTextField.text!, block: { (user, error) in
activityIndicator.stopAnimating()
UIApplication.shared.endIgnoringInteractionEvents()
if error != nil {
var displayErrorMessage = "Please try again later."
let error = error as NSError?
if let errorMessage = error?.userInfo["error"] as? String {
displayErrorMessage = errorMessage
}
self.createAlert(title: "Sign in error", message: displayErrorMessage)
} else {
print("Logged in")
self.performSegue(withIdentifier: "toSignIn", sender: self)
}
})
}
}
更新：这是整个视图控制器
class ViewController: UIViewController {
@IBOutlet var usernameTextField: UITextField!
@IBOutlet var passwordTextField: UITextField!
func createAlert(title: String, message: String) {
let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { (action) in
self.dismiss(animated: true, completion: nil)
}))
self.present(alert, animated: true, completion: nil)
}
@IBAction func signInPressed(_ sender: Any) {
if usernameTextField.text == "" || passwordTextField.text == "" {
createAlert(title: "Error in form", message: "Please enter an email and password.")
} else {
var activityIndicator = UIActivityIndicatorView()
activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
activityIndicator.center = self.view.center
activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
view.addSubview(activityIndicator)
activityIndicator.startAnimating()
UIApplication.shared.beginIgnoringInteractionEvents()
PFUser.logInWithUsername(inBackground: usernameTextField.text!, password: passwordTextField.text!, block: { (user, error) in
activityIndicator.stopAnimating()
UIApplication.shared.endIgnoringInteractionEvents()
if error != nil {
var displayErrorMessage = "Please try again later."
let error = error as NSError?
if let errorMessage = error?.userInfo["error"] as? String {
displayErrorMessage = errorMessage
}
self.createAlert(title: "Sign in error", message: displayErrorMessage)
} else {
print("Logged in")
self.performSegue(withIdentifier: "toSignIn", sender: self)
}
})
}
}
override func viewDidAppear(_ animated: Bool) {
if PFUser.current() != nil {
performSegue(withIdentifier: "toSignIn", sender: self)
}
self.tabBarController?.tabBar.isHidden = true
}
override func viewDidLoad() {
super.viewDidLoad()
}
【问题讨论】：
-
您可能在
viewDidLoad或其他地方调用createAlert。您能否添加您的整个视图控制器代码？ -
@PranavKasetti 我已经用整个视图控制器代码更新了我的帖子
-
好的。您使用 segue 导航到哪个视图控制器？
-
@PranavKasetti 到标签栏控制器视图
-
为什么
self.dismiss(animated: true, completion: nil)在你的UIAlertAction的完成处理程序中？如果您将完成处理程序声明为nil和self是指在此上下文中显示警报的视图控制器，则警报会自动解除，因此您不会像那样解除警报。
标签： ios swift uialertcontroller