ios - 仅当文本字段为空时如何显示图像？

Question

我有 4 个文本字段、一个按钮和一个图像，我想要实现的是，当按下按钮时，它应该警告用户有空文本字段，并显示指向空文本字段的图像，但当用户将文本放入空文本字段时使图像消失。谢谢

这是我的功能

func checkFields(){
    let userEmail = user_EmailTxtField.text!
    let userPassword = user_PassTxtField.text!
    let passwordConfirm = pass_ConfirmTxtField.text!
    let userPhone = user_PhoneTxtField.text!
    //Set backArrow image to show input error to password
    let imageName = "backArrow.png"
    let image = UIImage(named: imageName)
    let passImageView1 = UIImageView(image: image!)
    passImageView1.frame = CGRect(x: 319, y: 331, width: 49, height: 49)
    view.addSubview(passImageView1)
    //Show Arrow image to password confirm error
    let passConfirmImageView1 = UIImageView(image: image!)
    passConfirmImageView1.frame = CGRect(x: 319, y: 394, width: 49, height: 49)
    view.addSubview(passConfirmImageView1)
    //Show arrow Image to email error
    let emailImageView1 = UIImageView(image: image!)
    emailImageView1.frame = CGRect(x: 319, y: 270, width: 49, height: 49)
    view.addSubview(emailImageView1)
    //Set image to phonetxt field error
    let phoneImageView1 = UIImageView(image: image!)
    phoneImageView1.frame = CGRect(x: 319, y: 209, width: 49, height: 49)
    view.addSubview(phoneImageView1)
    if userPhone.isEmpty {
        phoneImageView1.isHidden = false
    } else {
        phoneImageView1.isHidden = true
    }
    if userEmail.isEmpty {
        emailImageView1.isHidden = false
    }
    if userPassword.isEmpty {
        passImageView1.isHidden = false
    }
    if passwordConfirm.isEmpty {
        passConfirmImageView1.isHidden = false
    }
}

Answer 1

您可以调用一个函数来处理您的检查，然后如果文本不为空，则隐藏您的图像，如下所示:

1 将目标添加到您为事件创建文本字段的位置 .editingChanged:

user_EmailTxtField.addTarget(self, action: #selector(textFieldDidChange), for: .editingChanged)
user_PhoneTxtField.addTarget(self, action: #selector(textFieldDidChange), for: .editingChanged)
pass_ConfirmTxtField.addTarget(self, action: #selector(textFieldDidChange), for: .editingChanged)
pass_ConfirmTxtField.addTarget(self, action: #selector(textFieldDidChange), for: .editingChanged)

2 设置用于检查文本字段是否被编辑的方法:

func textFieldDidChange() {
  emailImageView1.isHidden = user_EmailTxtField.hasText
  phoneImageView1.isHidden = user_PhoneTxtField.hasText
  passImageView1.isHidden = pass_ConfirmTxtField.hasText
  passConfirmImageView1.isHidden = pass_ConfirmTxtField.hasText
}

因此，如果您将此示例应用于所有文本字段，则不需要 checkFields() 中的检查，并且可以将方法重命名为 setupTextFields()例如仅将其用作文本字段的创建

在类的所有方法中使用 ImageView 的示例，但请务必在 viewDidLoad() 中进行初始化，以避免在解包可选值时出现发现 nil 错误

class YourClass: UIViewController {

  // ImageView Reference
  var emailImageView1: UIImageView!

  // then your checkFields method
  func checkFields() {
    // code before
    emailImageView1 = UIImageView(image: image!)
    // code after
  }
}