处理 Parse 中的某些错误

Question

我希望在我的程序中出现某些错误代码时创建某些事件。例如，如果出现错误代码 200，我需要让用户知道他们缺少用户名字段。或者对于错误代码 125，我需要让他们知道他们在创建帐户时没有输入有效的电子邮件地址。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未解决的标识符“错误”。在解析启动项目文件“AppDelegate.swift”中有一个这样的实例，它调用以下代码，它似乎工作得很好。

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

在您的代码所在的位置没有定义error。您只能在 error 存在的范围内引用它。

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 已经指出的那样，UIAlertView 已被弃用，因此您应该使用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)
}