我最近从 Swift 2 切换到 Swift 3，我的 signInWithLogin 收到错误消息。我是初学者并尝试阅读此内容，但似乎这行代码并没有真正改变，所以我不确定为什么会出现错误以及如何解决。错误似乎出现在 -> in 所在的位置。这是新东西吗？
import UIKit
class LoginViewController: UIViewController, UITextFieldDelegate {
let invalidNetwork = "Oh Snap! You Don't Have Internet!"
@IBOutlet var usernameField: UITextField!
@IBOutlet var passwordField: UITextField!
@IBOutlet var loginButton: UIButton!
@IBOutlet var errorLabel: UILabel!
@IBOutlet var imageView: UIImageView!
var activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView()
func displayAlert(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)
}
override func viewDidLoad() {
tapOutKeyboard()
let spacerView = UIView(frame:CGRect(x:0, y:0, width:20, height:10))
usernameField.leftViewMode = UITextFieldViewMode.always
usernameField.leftView = spacerView
let anotherSpacerView = UIView(frame:CGRect(x:0, y:0, width:20, height:10))
passwordField.leftViewMode = UITextFieldViewMode.always
passwordField.leftView = anotherSpacerView
usernameField.delegate = self
passwordField.delegate = self
}
@IBAction func signupButton(_ sender: Any) {
_ = self.storyboard?.instantiateViewController(withIdentifier: "SignupViewController")
UIApplication.shared.openURL(URL(string: url.URL)!)
}
struct url {
static let URL = "https://www.udacity.com/account/auth#!/signup"
}
@IBAction func loginButton(_ sender: Any) {
dismissKeyboard()
self.view.endEditing(true)
if usernameField.text == "" || passwordField.text == "" {
displayAlert(title: "Oh Snap!", message: "Something Went Wrong! Try Again!")
} else {
activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
activityIndicator.center = self.view.center
activityIndicator.hidesWhenStopped = true
activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyle.gray
view.addSubview(activityIndicator)
activityIndicator.startAnimating()
UIApplication.shared.beginIgnoringInteractionEvents()
}
let spinner = showSpinner()
UdacityAPI.signInWithLogin(usernameField.text!, password: passwordField.text!) { (user, error) -> in
spinner.hide()
if user != nil {
//Logged In!
self.performSegue(withIdentifier: "login", sender: self)
//Present The Map And Tabbed View
if let tabBarVC = self.storyboard?.instantiateViewController(withIdentifier: "TabBarViewController") {
self.present(tabBarVC, animated: true, completion: nil)
}
} else {
self.displayAlert(title: "Failed Logging In!", message: errorMessage)
}
if let response = user as? HTTPURLResponse {
if response.statusCode < 200 || response.statusCode > 300 {
self.displayAlert(title: "Try Again Later!", message: "Error!")
return
}
}
if let error = error {
//Network Error
if error.code == NSURLErrorNotConnectedToInternet {
let alertViewMessage = self.invalidNetwork
let okActionAlertTitle = "OK"
self.presentAlert("Not Online!", message: alertViewMessage, actionTitle: okActionAlertTitle, actionHandler: nil)
}
}
}
}
}
最佳答案
是的，您在 -> 之后缺少返回类型。查看您的代码，我敢打赌这应该是 Void，但我不能肯定地说，因为我没有您的 API 的文档。
尝试像这样添加 Void:
UdacityAPI.signInWithLogin(usernameField.text!, password: passwordField.text!) { (user, error) -> Void in
关于ios - signInWithLogin 预期表达式，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42254195/