更新为 Swift 3及以上版本:

//1. Create the alert controller.
let alert = UIAlertController(title: "Some Title", message: "Enter a text", preferredStyle: .alert)


//2. Add the text field. You can configure it however you need.
alert.addTextField { (textField) in
textField.text = "Some default text"
}


// 3. Grab the value from the text field, and print it when the user clicks OK.
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { [weak alert] (_) in
let textField = alert.textFields![0] // Force unwrapping because we know it exists.
print("Text field: \(textField.text)")
}))


// 4. Present the alert.
self.present(alert, animated: true, completion: nil)

Swift 2. x

假设你想在 iOS 上收到行动警报:

//1. Create the alert controller.
var alert = UIAlertController(title: "Some Title", message: "Enter a text", preferredStyle: .Alert)


//2. Add the text field. You can configure it however you need.
alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
textField.text = "Some default text."
})


//3. Grab the value from the text field, and print it when the user clicks OK.
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { [weak alert] (action) -> Void in
let textField = alert.textFields![0] as UITextField
println("Text field: \(textField.text)")
}))


// 4. Present the alert.
self.presentViewController(alert, animated: true, completion: nil)

Swift 5

为方便起见，您可以使用下面的扩展。

ViewController中的用法:

showInputDialog(title: "Add number",
subtitle: "Please enter the new number below.",
actionTitle: "Add",
cancelTitle: "Cancel",
inputPlaceholder: "New number",
inputKeyboardType: .numberPad, actionHandler:
{ (input:String?) in
print("The new number is \(input ?? "")")
})

扩展代码:

extension UIViewController {
func showInputDialog(title:String? = nil,
subtitle:String? = nil,
actionTitle:String? = "Add",
cancelTitle:String? = "Cancel",
inputPlaceholder:String? = nil,
inputKeyboardType:UIKeyboardType = UIKeyboardType.default,
cancelHandler: ((UIAlertAction) -> Swift.Void)? = nil,
actionHandler: ((_ text: String?) -> Void)? = nil) {
        

let alert = UIAlertController(title: title, message: subtitle, preferredStyle: .alert)
alert.addTextField { (textField:UITextField) in
textField.placeholder = inputPlaceholder
textField.keyboardType = inputKeyboardType
}
alert.addAction(UIAlertAction(title: actionTitle, style: .default, handler: { (action:UIAlertAction) in
guard let textField =  alert.textFields?.first else {
actionHandler?(nil)
return
}
actionHandler?(textField.text)
}))
alert.addAction(UIAlertAction(title: cancelTitle, style: .cancel, handler: cancelHandler))
        

self.present(alert, animated: true, completion: nil)
}
}

在 Swift5和 Xcode 10中

使用 Save 和 Cancel 操作和 读取文本字段文本数据添加两个文本字段

func alertWithTF() {
//Step : 1
let alert = UIAlertController(title: "Great Title", message: "Please input something", preferredStyle: UIAlertController.Style.alert )
//Step : 2
let save = UIAlertAction(title: "Save", style: .default) { (alertAction) in
let textField = alert.textFields![0] as UITextField
let textField2 = alert.textFields![1] as UITextField
if textField.text != "" {
//Read TextFields text data
print(textField.text!)
print("TF 1 : \(textField.text!)")
} else {
print("TF 1 is Empty...")
}


if textField2.text != "" {
print(textField2.text!)
print("TF 2 : \(textField2.text!)")
} else {
print("TF 2 is Empty...")
}
}


//Step : 3
//For first TF
alert.addTextField { (textField) in
textField.placeholder = "Enter your first name"
textField.textColor = .red
}
//For second TF
alert.addTextField { (textField) in
textField.placeholder = "Enter your last name"
textField.textColor = .blue
}


//Step : 4
alert.addAction(save)
//Cancel action
let cancel = UIAlertAction(title: "Cancel", style: .default) { (alertAction) in }
alert.addAction(cancel)
//OR single line action
//alert.addAction(UIAlertAction(title: "Cancel", style: .default) { (alertAction) in })


self.present(alert, animated:true, completion: nil)


}

更多解释

快速版: 5. +

在当前范围内创建一个新的 TextField变量，并将其分配给 alert.addTextField完成处理程序中的 alertTextField。在 UIAlertAction完成处理程序中使用 textField的值。

@IBAction func addButtonPressed(_ sender: UIBarButtonItem) {
//Variable to store alertTextField
var textField = UITextField()
            

let alert = UIAlertController(title: "Add new item", message: "", preferredStyle: .alert)
alert.addTextField { alertTextField in
alertTextField.placeholder = "Create new item"
                

//Copy alertTextField in local variable to use in current block of code
textField = alertTextField
}
            

let action = UIAlertAction(title: "Add item", style: .default) { action in
//Prints the alertTextField's value
print(textField.text!)
}
            

alert.addAction(action)
present(alert, animated: true, completion: nil)
}

let ac = UIAlertController(title: "title", message: "message", preferredStyle: .alert)
ac.addTextField()


let submitAction = UIAlertAction(title: "Submit", style: .default) { [weak self, weak ac] action in
guard let wordToget = ac?.textFields?[0].text else { return }
//here you can do what you need like
print(wordToget)
}


ac.addAction(submitAction)
present(ac, animated: true)