在解析中處理某些錯誤

Question

我正在尋找在某些錯誤代碼出現在我的程序中時創建某些事件。例如，如果有錯誤代碼200，我需要讓用戶知道他們錯過了用戶名字段。或者對於錯誤代碼125，我需要讓他們知道在創建帳戶時他們沒有輸入有效的電子郵件地址。我如何專門針對這些錯誤代碼？我試過下面的代碼沒有成功，我做錯了什麼，這可能嗎？

if error.code == 125 { 
     var invalidEmail:UIAlertView = UIAlertView(title: Please try again, message: "That does not look like a real email address. Please enter a real one.", delegate: self, cancelButtonTitle: "Try again") 
     invalidEmail.show() 
    } 

xCode告訴我的錯誤是我有一個無法解析的標識符'錯誤'。在解析啓動器項目文件'AppDelegate.swift'中有一個這樣的實例，它調用以下代碼，它似乎很好地工作。

func application(application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: NSError) { 
    if error.code == 3010 { 
     println("Push notifications are not supported in the iOS Simulator.") 
    } else { 
     println("application:didFailToRegisterForRemoteNotificationsWithError: %@", error) 
    } 
} 

我的代碼

@IBAction func signupTapped(sender: AnyObject) { 

    let fullname = fullnameField.text 
    let email = emailField.text 
    let username = usernameField.text 
    let password = passwordField.text 

    var user = PFUser() 
    user.username = username 
    user.password = password 
    user.email = email 
    // other fields can be set just like with PFObject 
    user["fullname"] = fullname 

    if error.code == 125 { 
     let alert = UIAlertController(title: "Please try again", message: "That does not look like a valid email address.", preferedStyle: .Alert) 
     alert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil)) 
     presentViewController(alert, animated: true) 
    } 

    if fullname.isEmpty || email.isEmpty || username.isEmpty || password.isEmpty { 
     let emptyFieldsError:UIAlertView = UIAlertView(title: "Please try again", message: "Please fill out all the fields so that we can create your account.", delegate: self, cancelButtonTitle: "Try again") 
     emptyFieldsError.show() 
    } 

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

Answer 1

沒有定義error，你有你的代碼。您只能在其存在的範圍內引用error。

user.signUpInBackgroundWithBlock { 
    (succeeded: Bool, error: NSError?) -> Void in 
    if let error = error { 
     let errorString = error.userInfo?["error"] as? NSString 
     // PUT YOUR ERROR HANDLING CODE HERE 
    } else { 

    } 
} 

Answer 2

正如@Larme已經指出，UIAlertView已過時，所以你應該使用UIAlertController：

if error.code == 125 { 
    let alert = UIAlertController(title: "Please try again", message: "That does not look like a valid email address.", preferedStyle: .Alert) 
    alert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: nil)) 
    presentViewController(alert, animated: true) 
}