Ios 如何根据UITextField禁用UIAlertAction?
我有一个Ios 如何根据UITextField禁用UIAlertAction?,ios,swift,uitextfield,action,uialertview,Ios,Swift,Uitextfield,Action,Uialertview,我有一个操作,当点击按钮时,它会创建一个警报 此警报由两个文本字段和两个操作(添加和解除)组成 如果文本字段为空,有没有简单的方法可以禁用添加按钮(稍后我会检查第二个字段是否真的是URL,但让我们关注操作 以下是我的代码和我迄今为止尝试的内容: @IBAction func addSourceTapped(_ sender: Any) { let alert = UIAlertController(title: "Add a News Source", message: nil, pr
操作
,当点击按钮时,它会创建一个警报
此警报
由两个文本字段
和两个操作
(添加
和解除
)组成
如果文本字段
为空,有没有简单的方法可以禁用添加
按钮(稍后我会检查第二个字段是否真的是URL,但让我们关注操作
以下是我的代码和我迄今为止尝试的内容:
@IBAction func addSourceTapped(_ sender: Any) {
let alert = UIAlertController(title: "Add a News Source", message: nil, preferredStyle: .alert)
alert.addTextField { (textField) in
textField.placeholder = "Name"
}
alert.addTextField { (textField) in
textField.placeholder = "Link"
}
let name = alert.textFields!.first!.text!
let link = alert.textFields!.last!.text!
if name != "" && link != "" {
alert.actions[0].isEnabled = true
}
let action = UIAlertAction(title: "Add", style: .default) { (_) in
let name = alert.textFields!.first!.text!
let link = alert.textFields!.last!.text!
if name != "" && link != "" {
alert.actions[0].isEnabled = true //doesn't do anything yet..
if CoreDataHandler.saveSource(name: "\(name)", link: "\(link)") {
for _ in CoreDataHandler.fetchSource()! {
}
}
}
self.tableView.reloadData()
}
let action2 = UIAlertAction(title: "Dismiss", style: .default)
alert.addAction(action)
alert.actions[0].isEnabled = false
alert.addAction(action2)
present(alert, animated: true, completion: nil)
}
您不能在任何地方编写UITextField验证代码(用于启用/禁用操作的代码)!!。每次更新UItextfield时都必须进行此验证。因此,要做到这一点,您需要从UITextField获取委托以进行更新 您需要全局保存文本字段,并将文本字段的委托分配给ViewController。通过这样做,您可以编写代码来验证UIViewController中文本字段的代码,并以编程方式启用或禁用您的操作
class YOUR_CLASS_NAME:UIViewController,UITextFieldDelegate {
var alert: UIAlertController!
var action: UIAlertAction!
var action2: UIAlertAction!
var nameTextFeld:UITextField!
var linkTextFeld:UITextField!
@IBAction func addSourceTapped(_ sender: Any) {
alert = UIAlertController(title: "Add a News Source", message: nil, preferredStyle: .alert)
alert.addTextField { (textField) in
self.nameTextFeld = textField
self.nameTextFeld.placeholder = "Name"
self.nameTextFeld.delegate = self
}
alert.addTextField { (textField) in
self.linkTextFeld = textField
self.linkTextFeld.placeholder = "Link"
self.linkTextFeld.delegate = self
}
action = UIAlertAction(title: "Add", style: .default) { (_) in
let name = self.alert.textFields!.first!.text!
let link = self.alert.textFields!.last!.text!
if CoreDataHandler.saveSource(name: "\(name)", link: "\(link)") {
for _ in CoreDataHandler.fetchSource()! {
}
}
self.tableView.reloadData()
}
action.isEnabled = false
action2 = UIAlertAction(title: "Dismiss", style: .default)
alert.addAction(action)
alert.actions[0].isEnabled = false
alert.addAction(action2)
present(alert, animated: true, completion: nil)
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if !((nameTextFeld.text?.isEmpty)! && (linkTextFeld.text?.isEmpty)!) {
action.isEnabled = true
}
return true
}
}
通过在添加文本字段时配置文本字段来完成此操作
alert.addTextField(configurationHandler: { (textField) -> Void in
textField.placeholder = "Name"
// Other configuration such as textField.autocapitalizationType = .words
NotificationCenter.default.addObserver(forName: NSNotification.Name.UITextFieldTextDidChange, object: textField, queue: OperationQueue.main) { (notification) in
let nameField = alert.textFields![0] as UITextField
let linkField = alert.textFields![1] as UITextField
action.isEnabled = self.getTextFieldContent(nameField) != "" && self.getTextFieldContent(linkField) != ""
}
})
您需要对这两个文本字段分别执行此操作(尽管您可以通过重用相同的代码来执行此操作)。另外请注意,如果您直接在操作的处理程序块中引用textfields,它将创建一个强引用循环,并且您的控制器将不会被取消命名。要避免这种情况,请使用如下局部可为null的变量引用文本字段
var tf: UITextField?
let action = UIAlertAction(title: "Add", style: .default) { (_) in
guard let textField = tf else {
return;
}
let name = textField.text!
// Rest the action here
}
alertController.addTextField { (textField) in
// Configure textField here
tf = textField
}
你应该更好地使用行动,它比其他答案更简单。如果您尝试使用委托,那么didBeginEditing和didebendediting方法将无法正确处理它。也不应更改字符在范围内,它在textfield中出现输入之前执行,因此在此处检查textfield的text属性是不正确的
private var action: UIAlertAction!
@IBAction func addSourceTapped(_ sender: Any) {
////////
let alert = UIAlertController(title: "Add a News Source", message: nil, preferredStyle: .alert)
alert.addTextField { (textField) in
textField.placeholder = "Name"
textField.addTarget(self, action: #selector(self.textFieldDidChange(_:)), for: .editingChanged) // <---
}
action = UIAlertAction(title: "Add", style: .default) { (_) in
/////
}
action.isEnabled = false
alert.addAction(action)
////////
}
@objc private func textFieldDidChange(_ field: UITextField) {
action.isEnabled = field.text?.count ?? 0 > 0
}
private var action:UIAlertAction!
@iAction func addSourceTapped(\发送方:任何){
////////
let alert=UIAlertController(标题:“添加新闻源”,消息:nil,preferredStyle:.alert)
alert.addTextField{(textField)位于
textField.placeholder=“名称”
textField.addTarget(self,action:#选择器(self.textFieldDidChange(:)),for:.editingChanged)//0
}
使用操作的编程解决方案。
将按钮添加到类中,并根据文本字段中所做的更改继续更改其状态
import UIKit
final class ViewWithConfirmationController: UIViewController {
private let askButton = UIButton()
private let deleteAction = UIAlertAction(
title: "Confirm",
style: .default
) { _ in
// Confirmed
}
init() {
super.init(nibName: nil, bundle: nil)
view.addSubview(askButton)
askButton.setTitle("Call alert", for: .normal)
askButton.addTarget(
self,
action: #selector(callAlert),
for: .touchUpInside
)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
@objc func callAlert() {
let alert = UIAlertController(
title: "Confirmation alert",
message: """
Do you really want to do that?
Please type in the magic word to confirm.
""",
preferredStyle: .alert
)
alert.addTextField { textField in
textField.placeholder = "Magic word"
textField.addTarget(
self,
action: #selector(self.textFieldDidChange(_:)),
for: .editingChanged
)
}
alert.addAction(
UIAlertAction(
title: "Cancel",
style: .cancel,
handler: { _ in }
))
alert.addAction(deleteAction)
// Confirm button will disabled until user type current organisation name
deleteAction.isEnabled = false
present(alert, animated: true, completion: nil)
}
@objc private func textFieldDidChange(_ field: UITextField) {
guard let text = field.text else {
print("Can't get text from text field in \(#function)")
return
}
deleteAction.isEnabled = !text.isEmpty
}
}
您可以使全局可选的alertview cotroller可变,然后您可以在in-textfield delegate Methods中管理验证。这很好!您知道为什么单击“添加”时,
self.tableView.reloadData()
不再起作用了吗?