在解析中处理某些错误

Question

我正在寻找在某些错误代码出现在我的程序中时创建某些事件。例如，如果有错误代码200，我需要让用户知道他们错过了用户名字段。或者对于错误代码125，我需要让他们知道在创建帐户时他们没有输入有效的电子邮件地址。我如何专门针对这些错误代码？我试过下面的代码没有成功，我做错了什么，这可能吗？

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告诉我的错误是我有一个无法解析的标识符'错误'。在解析启动器项目文件'AppDelegate.swift'中有一个这样的实例，它调用以下代码，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) 
    } 
} 

我的代码

@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

没有定义error，你有你的代码。您只能在其存在的范围内引用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已经指出，UIAlertView已过时，所以你应该使用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) 
}