Question

我正在尝试使用xib文件来显示自定义更改视图。为此，我使用here中的SimpleAlert。我有.xib文件，其中包含textFields，并且作为.xib的所有者，我设置了ViewController。

import UIKit

class TestBaumViewController: UIViewController, UITextFieldDelegate {

@IBOutlet weak var tfFirst: UITextField!
@IBOutlet weak var tfSecond: UITextField!
@IBOutlet weak var tfThird: UITextField!
@IBOutlet weak var tfFourth: UITextField!


init() {
    super.init(nibName: "TestBaumViewController", bundle: nil)
    initializeTextFields()
}

required init(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    //initializeTextFields()
}

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    //initializeTextFields()
}

override func awakeFromNib() {
    super.awakeFromNib()
    //initializeTextFields()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func initializeTextFields() {
    tfFirst.delegate = self // Error Here!
    tfFirst.keyboardType = UIKeyboardType.ASCIICapable

    tfSecond.delegate = self
    tfSecond.keyboardType = UIKeyboardType.NumberPad

    tfThird.delegate = self
    tfThird.keyboardType = UIKeyboardType.ASCIICapable

    tfFourth.delegate = self
    tfFourth.keyboardType = UIKeyboardType.NumberPad
}

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
    var result = true
    let prospectiveText = (textField.text as NSString).stringByReplacingCharactersInRange(range , withString: string)

    if textField == tfFirst {
        if count(string) > 0 {
            let disallowedCharacterSet = NSCharacterSet(charactersInString: "BW").invertedSet
            let replacementStringIsLegal = string.rangeOfCharacterFromSet(disallowedCharacterSet) == nil

            let resultingStringLengthIsLegal = count(prospectiveText) <= 1

            result = replacementStringIsLegal && resultingStringLengthIsLegal
        }
    }

    if textField == tfSecond {
        if count(string) > 0 {
            let disallowedCharacterSet = NSCharacterSet(charactersInString: "0123456789").invertedSet
            let replacementStringIsLegal = string.rangeOfCharacterFromSet(disallowedCharacterSet) == nil

            let resultingStringLenthIsLegel = count(prospectiveText) <= 3

            result = replacementStringIsLegal && resultingStringLenthIsLegel
        }
    }

    if textField == tfThird {
        if count(string) > 0 {
            let disallowedCharacterSet = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyz").invertedSet
            let replacementStringIsLegal = string.rangeOfCharacterFromSet(disallowedCharacterSet) == nil

            let resultingStringLenthIsLegel = count(prospectiveText) <= 1

            result = replacementStringIsLegal && resultingStringLenthIsLegel
        }
    }

    if textField == tfFourth {
        if count(string) > 0 {
            let disallowedCharacterSet = NSCharacterSet(charactersInString: "0123456789").invertedSet
            let replacementStringIsLegal = string.rangeOfCharacterFromSet(disallowedCharacterSet) == nil

            let resultingStringLenthIsLegel = count(prospectiveText) <= 3

            result = replacementStringIsLegal && resultingStringLenthIsLegel
        }
    }
    return result
}

正如您所看到的，我为我的文本字段添加了IBOutlets，现在我想将此视图控制器添加为其委托。所以我可以查看在文本字段中输入的内容。

我尝试了不同的方法。首先我尝试将textfield.delegate = self放入viewDidLoad方法，但是我得到一个错误“致命错误：在解开一个Optional值时意外发现nil”我认为这是因为textfield不是jet创建的。接下来，它尝试了viewDidAppear方法，结果相同。最后，在我将一个Object添加到.xib并将视图控制器类设置为其类以使awakeFromNib方法触发之后，我将textfield.delegate = self放入该方法中。但我在这里得到了同样的错误。

我有没有想到的事情，或者我正在做一些不起作用的事情？

尊重阿达卡斯

Answer 1

由于您已经声明您的控制器符合UITextFieldDelegate协议，请在Interface Builder中执行此操作：

选择文字字段
显示连接检查器
下面会有一个Outlets部分，其中包含delegate。
将delegate右侧的圆圈拖动到View Controller对象，如

enter image description here

为每个textField执行此操作

现在应该正确调用textField委托方法。

Answer 2

didSet怎么样？

class TestBaumViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var tfFirst: UITextField! {
        didSet {
            tfFirst.delegate = self
        }
    }
...

或者您也可以在XIB中拖动文本字段委托。右键单击文本字段并将delegate属性拖到视图控制器。

在ViewController中为.xib

2 个答案: