ios - 如何在 UITextfield 数据为空或已填充时禁用/启用按钮？

Question

这是我的功能。正如您在上面看到的，当文本字段为空(或 nil)并且按钮被禁用时，我能够在控制台中收到一条消息。但是，当在我的文本字段中输入数据时，我没有收到回复。如果有人可以帮助我解决这个问题或类似的问题，我将不胜感激。

func logicDataCheck() {
    let textfield: Array<Bool?> = [lastNameTextField.text?.isEmpty, phoneNumberTextField.text?.isEmpty, firstNameTextField.text?.isEmpty]

    if (textfield[0]! || textfield [1]! || textfield [2]!)
    {
        print("Textfield is empty")
        continue_Button.isEnabled = false
        continue_Button.alpha = 0.5
    }
    else 
    {
        if (textfield[0]! || textfield [1]! || textfield [2]!) {
            print("Textfield is full")
            continue_Button.isEnabled = true
            continue_Button.alpha = 1
        }
    }
}

Answer 1

在您的 viewDidLoad 中，您可以添加以下行:

configureTextFields()
// you'll need to call updateTextField() when the view loads the first time.
// After the configureTextFields() adds targets, it'll get called when editing changes
updateTextField()

此外，添加这些方法:

func configureTextFields() {
    // create an array of textfields
    let textFieldArray = [firstNameTextField, lastNameTextField, phoneNumberTextField]

    // configure them...
    for textField in textFieldArray {
        // make sure you set the delegate to be self
        textField?.delegate = self
        // add a target to them
        textField?.addTarget(self, action: #selector(ViewController.updateTextField), for: .editingChanged)
    }
}

// this is the target that gets called when editing changes
func updateTextField() {
    // create an array of textFields
    let textFields = [firstNameTextField, lastNameTextField, phoneNumberTextField]
    // create a bool to test if a textField is blank in the textFields array
    let oneOfTheTextFieldsIsBlank = textFields.contains(where: {($0?.text ?? "").isEmpty})
    if oneOfTheTextFieldsIsBlank {
        continueButton.isEnabled = false
        continueButton.alpha = 0.5
    } else {
        continueButton.isEnabled = true
        continueButton.alpha = 1.0
    }
}

您需要让您的 ViewController 采用 UITextFieldDelegate 协议(protocol)。你可以这样做:

class ViewController: UIViewController, UITextFieldDelegate {
// the code inside your view controller
}

这里是一个链接 demo I created on GitHub