不调用UITextField委托方法

Question

我正在用UITextfield呈现警报，但其委托方法没有被调用。我可能会做什么错误。我正在使用下面的代码来显示带有文本字段的警报。

func takePasscodeToEnableTouch(){ 
    self.passcodeInputOperationType = .EnableTouchID 

    alertControllerPassCodeEntry = UIAlertController(title: "", message: "Enter Passcode to enable the Touch Id.", preferredStyle: UIAlertControllerStyle.Alert) 

    let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel) { (action) -> Void in 
    } 
    alertControllerPassCodeEntry!.addAction(cancelAction) 

    alertControllerPassCodeEntry!.addTextFieldWithConfigurationHandler { (txtField) -> Void in 
     txtField.placeholder = "Enter passcode" 
     txtField.delegate = self 
     txtField.tag = TextFieldTag.EnterPassCode 
     txtField.keyboardType = UIKeyboardType.NumbersAndPunctuation 
     txtField.accessibilityIdentifier = "PassCode" 
     txtField.secureTextEntry = true 
     txtField.addTarget(self, action:"textFieldDidChange:", forControlEvents: UIControlEvents.EditingChanged) 
    } 

    let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate 
    appDelegate.window?.rootViewController?.presentViewController(alertControllerPassCodeEntry!, animated: true, completion: nil) 
} 

而且文本框的委托方法：

func textFieldShouldBeginEditing(textField: UITextField) -> Bool 
{ 
    return true 
} 

func textFieldDidBeginEditing(textField: UITextField) // became first responder 
{ 

} 

func textFieldShouldEndEditing(textField: UITextField) -> Bool 
{ 
    return true 
} 

func textFieldDidEndEditing(textField: UITextField) 
{ 

} 

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool 
{ 
    var isLimitExist: Bool 
    var accessIndentifier: String 
    if let str = textField.accessibilityIdentifier 
    { 
     accessIndentifier = str 
    } 
    else 
    { 
     accessIndentifier = "" 
    } 

    //checkFieldLimit function is used to check the limit of text and restrict 
    isLimitExist = UIUtils.checkFieldLimit(accessIndentifier, stringToMatch: textField.text!, rangeLength: range.length, stringLength: string.characters.count) 

    if !isLimitExist 
    { 
     return false 
    } 
    return true 
} 

Answer 1

好了，从评论的信息，现在一切都似乎很清楚。总括来说，你调用显示这样的警报的方法：

@IBAction func swtchTouchAction(sender: UISwitch) { 
    if sender.on { 
     let passCodeManager = PasscodeManager() 
     passCodeManager.delegate = self 
     passCodeManager.takePasscodeToEnableTouch() 
    } else { 
     let passCodeManager = PasscodeManager() 
     passCodeManager.delegate = self 
     passCodeManager.authenticatePasscodeToDisalbeTouch() 
    } 
} 

现在，你不保留（意思是 - 分配到一个强大的属性）的passCodeManager在这里的任何地方。这意味着，在该方法结束时，该对象被破坏（感谢ARC - Automatic Reference Counting）。有人可能会认为它会被保留，因为您将其指定为文本字段的delegate，但代表的时间为99.99％，这意味着它们不会撞到分配给它们的对象的保留计数。

解决您的眼前问题，你应该在你的类中，你必须swtchTouchAction方法的属性，并更改你这样的代码：

var passCodeManager: PasscodeManager? 

@IBAction func swtchTouchAction(sender: UISwitch) { 
    if sender.on { 
     self.passCodeManager = PasscodeManager() 
     self.passCodeManager?.delegate = self 
     self.passCodeManager?.takePasscodeToEnableTouch() 
    } else { 
     self.passCodeManager = PasscodeManager() 
     self.passCodeManager?.delegate = self 
     self.passCodeManager?.authenticatePasscodeToDisalbeTouch() 
    } 
} 

这将足以保留您的密码管理器。我建议你阅读memory management is done in Swift。