如何在 Swift 中创建 UIAlertView？

从 UIAlertView 类：

// UIAlertView 已弃用。改用 UIAlertController 和 UIAlertControllerStyleAlert 的preferredStyle

在 iOS 8 上，您可以这样做：

let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)

现在，UIAlertController 是一个单一类，用于创建 iOS 8 上的 UIAlertView 和 UIActionSheet 并与之交互。

编辑：处理动作：

alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { action in
    switch action.style{
    case .Default:
        print("default")
        
    case .Cancel:
        print("cancel")
        
    case .Destructive:
        print("destructive")
    }
}}))

为 Swift 3 编辑：

let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)

为 Swift 4.x 编辑：

let alert = UIAlertController(title: "Alert", message: "Message", preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { action in
    switch action.style{
        case .default:
        print("default")
        
        case .cancel:
        print("cancel")
        
        case .destructive:
        print("destructive")
        
    }
}))
self.present(alert, animated: true, completion: nil)

---

一键式

https://i.stack.imgur.com/OSaIi.png

class ViewController: UIViewController {

    @IBAction func showAlertButtonTapped(_ sender: UIButton) {

        // create the alert
        let alert = UIAlertController(title: "My Title", message: "This is my message.", preferredStyle: UIAlertController.Style.alert)

        // add an action (button)
        alert.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))

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

两个按钮

https://i.stack.imgur.com/gmAj9.png

class ViewController: UIViewController {

    @IBAction func showAlertButtonTapped(_ sender: UIButton) {

        // create the alert
        let alert = UIAlertController(title: "UIAlertController", message: "Would you like to continue learning how to use iOS alerts?", preferredStyle: UIAlertController.Style.alert)

        // add the actions (buttons)
        alert.addAction(UIAlertAction(title: "Continue", style: UIAlertAction.Style.default, handler: nil))
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertAction.Style.cancel, handler: nil))

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

三个按钮

https://i.stack.imgur.com/aQgqD.png

class ViewController: UIViewController {

    @IBAction func showAlertButtonTapped(_ sender: UIButton) {

        // create the alert
        let alert = UIAlertController(title: "Notice", message: "Lauching this missile will destroy the entire universe. Is this what you intended to do?", preferredStyle: UIAlertController.Style.alert)

        // add the actions (buttons)
        alert.addAction(UIAlertAction(title: "Remind Me Tomorrow", style: UIAlertAction.Style.default, handler: nil))
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertAction.Style.cancel, handler: nil))
        alert.addAction(UIAlertAction(title: "Launch the Missile", style: UIAlertAction.Style.destructive, handler: nil))

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

处理按钮点击

在上述示例中，handler 是 nil。您可以将 nil 替换为 closure 以在用户点击按钮时执行某些操作。例如：

alert.addAction(UIAlertAction(title: "Launch the Missile", style: UIAlertAction.Style.destructive, handler: { action in

    // do something like...
    self.launchMissile()

}))

笔记

多个按钮不一定需要使用不同的 UIAlertAction.Style 类型。它们都可以是.default。

对于三个以上的按钮，请考虑使用操作表。设置非常相似。这是一个例子。

---

您可以使用标准构造函数创建 UIAlert，但“旧版”似乎不起作用：

let alert = UIAlertView()
alert.title = "Alert"
alert.message = "Here's a message"
alert.addButtonWithTitle("Understood")
alert.show()

---

在 Swift 4.2 和 Xcode 10 中

方法一：

简单的警报

let alert = UIAlertController(title: "Your title", message: "Your message", preferredStyle: .alert)
    
     let ok = UIAlertAction(title: "OK", style: .default, handler: { action in
     })
     alert.addAction(ok)
     let cancel = UIAlertAction(title: "Cancel", style: .default, handler: { action in
     })
     alert.addAction(cancel)
     DispatchQueue.main.async(execute: {
        self.present(alert, animated: true)
})

方法二：

共享类警报

如果你想要共享类风格（写一次使用每个地方）

import UIKit
class SharedClass: NSObject {//This is shared class
static let sharedInstance = SharedClass()

    //Show alert
    func alert(view: UIViewController, title: String, message: String) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        let defaultAction = UIAlertAction(title: "OK", style: .default, handler: { action in
        })
        alert.addAction(defaultAction)
        DispatchQueue.main.async(execute: {
            view.present(alert, animated: true)
        })
    }

    private override init() {
    }
}

现在在每个商品中都像这样调用警报

SharedClass.sharedInstance.alert(view: self, title: "Your title here", message: "Your message here")

方法3：

当前警报位于所有 WINDOWS 顶部

如果您想在所有视图之上显示警报，请使用此代码

func alertWindow(title: String, message: String) {
    DispatchQueue.main.async(execute: {
        let alertWindow = UIWindow(frame: UIScreen.main.bounds)
        alertWindow.rootViewController = UIViewController()
        alertWindow.windowLevel = UIWindowLevelAlert + 1
    
        let alert2 = UIAlertController(title: title, message: message, preferredStyle: .alert)
        let defaultAction2 = UIAlertAction(title: "OK", style: .default, handler: { action in
        })
        alert2.addAction(defaultAction2)
    
        alertWindow.makeKeyAndVisible()
    
        alertWindow.rootViewController?.present(alert2, animated: true, completion: nil)
    })
}

函数调用

SharedClass.sharedInstance.alertWindow(title:"This your title", message:"This is your message")

方法四：

带有扩展名的警报

extension  UIViewController {

    func showAlert(withTitle title: String, withMessage message:String) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        let ok = UIAlertAction(title: "OK", style: .default, handler: { action in
        })
        let cancel = UIAlertAction(title: "Cancel", style: .default, handler: { action in
        })
        alert.addAction(ok)
        alert.addAction(cancel)
        DispatchQueue.main.async(execute: {
            self.present(alert, animated: true)
        })
    }
}

现在这样调用

//Call showAlert function in your class
@IBAction func onClickAlert(_ sender: UIButton) {
    showAlert(withTitle:"Your Title Here", withMessage: "YourCustomMessageHere")
}

方法5：

带有文本字段的警报

如果要添加文本字段以提醒。

//Global variables
var name:String?
var login:String?

//Call this function like this:  alertWithTF() 
//Add textfields to alert 
func alertWithTF() {
    
    let alert = UIAlertController(title: "Login", message: "Enter username&password", preferredStyle: .alert)
    // Login button
    let loginAction = UIAlertAction(title: "Login", style: .default, handler: { (action) -> Void in
        // Get TextFields text
        let usernameTxt = alert.textFields![0]
        let passwordTxt = alert.textFields![1]
        //Asign textfileds text to our global varibles
        self.name = usernameTxt.text
        self.login = passwordTxt.text
        
        print("USERNAME: \(self.name!)\nPASSWORD: \(self.login!)")
    })
    
    // Cancel button
    let cancel = UIAlertAction(title: "Cancel", style: .destructive, handler: { (action) -> Void in })
    
    //1 textField for username
    alert.addTextField { (textField: UITextField) in
        textField.placeholder = "Enter username"
        //If required mention keyboard type, delegates, text sixe and font etc...
        //EX:
        textField.keyboardType = .default
    }
    
    //2nd textField for password
    alert.addTextField { (textField: UITextField) in
        textField.placeholder = "Enter password"
        textField.isSecureTextEntry = true
    }
    
    // Add actions
    alert.addAction(loginAction)
    alert.addAction(cancel)
    self.present(alert, animated: true, completion: nil)
    
}

方法六：

带有扩展名的 SharedClass 中的警报

//This is your shared class
import UIKit

 class SharedClass: NSObject {

 static let sharedInstance = SharedClass()

 //Here write your code....

 private override init() {
 }
}

//Alert function in shared class
extension UIViewController {
    func showAlert(title: String, msg: String) {
        DispatchQueue.main.async {
            let alert = UIAlertController(title: title, message: msg, preferredStyle: .alert)
            alert.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
            self.present(alert, animated: true, completion: nil)
        }
    }
}

现在直接这样调用

self.showAlert(title: "Your title here...", msg: "Your message here...")

方法七：

警报没有共享类，扩展在单独的类中进行警报。

创建一个新的 Swift 类和 import UIKit。复制并粘贴以下代码。

//This is your Swift new class file
import UIKit
import Foundation

extension UIAlertController {
    class func alert(title:String, msg:String, target: UIViewController) {
        let alert = UIAlertController(title: title, message: msg, preferredStyle: UIAlertControllerStyle.alert)
        alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default) {
        (result: UIAlertAction) -> Void in
        })
        target.present(alert, animated: true, completion: nil)
    }
}

现在在你的所有类（单行）中调用这样的警报函数。

UIAlertController.alert(title:"Title", msg:"Message", target: self)

如何....

---

点击查看

@IBAction func testClick(sender: UIButton) {

  var uiAlert = UIAlertController(title: "Title", message: "Message", preferredStyle: UIAlertControllerStyle.Alert)
  self.presentViewController(uiAlert, animated: true, completion: nil)

  uiAlert.addAction(UIAlertAction(title: "Ok", style: .Default, handler: { action in
   println("Click of default button")
  }))

  uiAlert.addAction(UIAlertAction(title: "Cancel", style: .Cancel, handler: { action in
   println("Click of cancel button")
  }))

}

用两个按钮确定和取消完成

---

如果您的目标是 iOS 7 和 8，您需要这样的东西来确保您为每个版本使用正确的方法，因为 UIAlertView 在 iOS 8 中已被弃用，但 UIAlertController在 iOS 7 中不可用：

func alert(title: String, message: String) {
    if let getModernAlert: AnyClass = NSClassFromString("UIAlertController") { // iOS 8
        let myAlert: UIAlertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
        myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
        self.presentViewController(myAlert, animated: true, completion: nil)
    } else { // iOS 7
        let alert: UIAlertView = UIAlertView()
        alert.delegate = self

        alert.title = title
        alert.message = message
        alert.addButtonWithTitle("OK")

        alert.show()
    }
}

---

使用 Swift 2 的协议扩展，您可以创建一个为您的视图控制器提供默认实现的协议：

ShowsAlert.swift

import UIKit

protocol ShowsAlert {}

extension ShowsAlert where Self: UIViewController {
    func showAlert(title: String = "Error", message: String) {
        let alertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
        alertController.addAction(UIAlertAction(title: "Ok", style: .Default, handler: nil))
        presentViewController(alertController, animated: true, completion: nil)
    }
}

ViewController.swift

class ViewController: UIViewController, ShowsAlert {
    override func viewDidLoad() {
        super.viewDidLoad()
        showAlert(message: "Hey there, I am an error message!")
    }
}

---

以 swift 语言显示 UIAlertView：-

协议 UIAlertViewDelegate

let alert = UIAlertView(title: "alertView", message: "This is alertView", delegate:self, cancelButtonTitle:"Cancel", otherButtonTitles: "Done", "Delete")
alert.show()

以 swift 语言显示 UIAlertViewController：-

let alert = UIAlertController(title: "Error", message: "Enter data in Text fields", preferredStyle: UIAlertControllerStyle.Alert)
alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))
self.presentViewController(alert, animated: true, completion: nil)

---

只需不要在构造函数中提供 otherButtonTitles。

let alertView = UIAlertView(title: "Oops!", message: "Something
happened...", delegate: nil, cancelButtonTitle: "OK")

alertView.show()

但我确实同意 Oscar，这个类在 iOS 8 中已被弃用，所以如果你正在做一个仅限 iOS 8 的应用程序，则不会使用 UIAlertView。否则上面的代码将起作用。

---

我找到了这个，

var alertView = UIAlertView();
alertView.addButtonWithTitle("Ok");
alertView.title = "title";
alertView.message = "message";
alertView.show();

虽然不好，但它的工作原理:)

更新：

但我在头文件中发现：

extension UIAlertView {
    convenience init(title: String, message: String, delegate: UIAlertViewDelegate?, cancelButtonTitle: String?, otherButtonTitles firstButtonTitle: String, _ moreButtonTitles: String...)
}

有人可以解释一下。

---

对于 SWIFT4，我认为，扩展 UIViewController 并创建可重用的确认控件是最优雅的方式。

您可以按如下方式扩展 UIViewController：

extension UIViewController {

func AskConfirmation (title:String, message:String, completion:@escaping (_ result:Bool) -> Void) {
    let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.alert)
    self.present(alert, animated: true, completion: nil)

    alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: { action in
        completion(true)
    }))

    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { action in
        completion(false)
    }))
  }
}

然后您可以随时使用它：

 AskConfirmation(title: "YOUR MESSAGE TITLE", message: "YOUR MESSAGE") { (result) in
        if result { //User has clicked on Ok

        } else { //User has clicked on Cancel

        }
    }

---

AlertView Swift 5 及更高版本：-

let alert = UIAlertController(title: LocalizedStringConstant.alert, message: message, preferredStyle: UIAlertController.Style.alert)
alert.addAction(UIAlertAction(title: "Retry", style: .cancel, handler: { (_) in
     }))
self.present(alert, animated: true, completion: nil)

---

适用于 iOS 13 Xcode 11+ Swift 5.X

UIAlertController 现在可以提供警报和操作表

警报

// First instantiate the UIAlertController

let alert = UIAlertController(title: "Title",
                              message: "Message ?",
                              preferredStyle: .alert)


 // Add action buttons to it and attach handler functions if you want to 

 alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
 alert.addAction(UIAlertAction(title: "Just Do It!", style: .destructive, handler: nil))
 alert.addAction(UIAlertAction(title: "Maybe", style: .default, handler: nil))

// Show the alert by presenting it

self.present(alert, animated: true)

请注意，所有操作按钮在点击时关闭警报视图是基本性质。 style 参数仅用于决定文本的颜色（以及按钮应出现的一些默认顺序，哪些 ofc 可以更改）

示例处理函数可以是

func handler(_ action: UIAlertAction) { 

   if action.title == 'Title' {
       // do stuff
   }

}

作为旁注，我会说不是制作 3 个不同的处理程序，您可以只制作 1 并以上面显示的方式追溯到引发它的元素我们也可以检查 alert.style 但是我们可以有多个 .default风格化的动作，我不建议这样做

行动表

解释是相似的，因为这里的主要区别是警报会打断用户，而操作表在 iPhone 中从底部滑动并在 iPad 中显示为弹出框

行动表的目的是指导用户根据他们当前的状态决定他的行动。所以你必须像十字路口一样对待行动表！通常没有消息，并且标题呈现为标题大小的文本

let action = UIAlertController(title: "What do you want to do with the message",
                               message: nil,
                               preferredStyle: .actionSheet)

action.addAction(UIAlertAction(title: "Cancel", style: .cancel)) 

for act in ["Save", "Post", "Discard"] {  
          action.addAction(UIAlertAction(title: act, style: .default, handler: nil))
}

self.present(action, animated: true)

上面的代码适用于 iPhone，但会在 iPad 运行时崩溃，因为 UIPopoverPresentationController 将负责警报，但不会参考当时的任何东西。因此，为避免这种情况，您必须提供以下代码块，这是强制性的

if let pop = action.popoverPresentationController {

     let v = sender as! UIView 
     pop.sourceView = v 
     pop.sourceRect = v.bounds
 }

此外，如果 iPad 轻按弹出框外的任何位置，则会将其关闭，并且会调用 .cancel 操作按钮的完成处理程序。

希望对您有所帮助:)话虽如此，如果您有任何疑问，请在下方评论

---

    class Preview: UIViewController , UIAlertViewDelegate
    {
        @IBAction func MoreBtnClicked(sender: AnyObject)
        {
            var moreAlert=UIAlertView(title: "Photo", message: "", delegate: self, cancelButtonTitle: "No Thanks!", otherButtonTitles: "Save Image", "Email", "Facebook", "Whatsapp" )
            moreAlert.show()
            moreAlert.tag=111;
        }

        func alertView(alertView: UIAlertView, didDismissWithButtonIndex buttonIndex: Int)
        {
            if alertView.tag==111
            {
                if buttonIndex==0
                {
                    println("No Thanks!")
                }
                else if buttonIndex==1
                {
                    println("Save Image")
                }
                else if buttonIndex == 2
                {
                    println("Email")
                }
                else if buttonIndex == 3
                {
                    println("Facebook")
                }
                else if buttonIndex == 4
                {
                    println("Whatsapp")
                }
            }
        }
    }

---

我还有一个技巧。假设您有 5 个要应用注销警报的类。尝试使用 swift 类扩展。

File-New-Swift 类-命名。

添加以下内容：

public extension UIViewController
{

    func makeLogOutAlert()
    {
        var refreshAlert = UIAlertController(title: "Log Out", message: "Are You Sure to Log Out ? ", preferredStyle: UIAlertControllerStyle.Alert)

        refreshAlert.addAction(UIAlertAction(title: "Confirm", style: .Default, handler: { (action: UIAlertAction!) in
            self.navigationController?.popToRootViewControllerAnimated(true)
        }))

        refreshAlert.addAction(UIAlertAction(title: "Cancel", style: .Default, handler: { (action: UIAlertAction!) in
            refreshAlert .dismissViewControllerAnimated(true, completion: nil)
        }))

        presentViewController(refreshAlert, animated: true, completion: nil)
    }
}

使用：self.makeLogOutAlert() 实现。希望能帮助到你。

---

我制作了一个单例类，以便在您的应用程序的任何地方都可以方便地使用它：https://github.com/Swinny1989/Swift-Popups

然后，您可以创建一个包含多个按钮的弹出窗口，如下所示：

Popups.SharedInstance.ShowAlert(self, title: "Title goes here", message: "Messages goes here", buttons: ["button one" , "button two"]) { (buttonPressed) -> Void in
    if buttonPressed == "button one" { 
      //Code here
    } else if buttonPressed == "button two" {
        // Code here
    }
}

或带有单个按钮的弹出窗口，如下所示：

Popups.SharedInstance.ShowPopup("Title goes here", message: "Message goes here.")

---

斯威夫特 3

以下是一个简单的示例，说明如何使用 Swift 3 使用一个按钮创建一个简单的警报。

let alert = UIAlertController(title: "Title",
                              message: "Message",
                              preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Ok", style: .default))
present(alert, animated: true)

在上面的示例中，操作的句柄回调已被省略，因为带有一个按钮的警报视图的默认行为是在单击按钮时消失。

以下是如何创建另一个操作，可以使用“alert.addAction(action)”将其添加到警报中。不同的样式是 .default、.破坏性和 .cancel。

let action = UIAlertAction(title: "Ok", style: .default) { action in
    // Handle when button is clicked    
}

---

我得到了以下 UIAlertView 初始化代码来编译而没有错误（我认为最后，可变部分可能很棘手）。但是我必须确保 self 的类（我作为委托传递）采用 UIAlertViewDelegate 协议才能消除编译错误：

let alertView = UIAlertView(
                  title: "My Title",
                  message: "My Message",
                  delegate: self,
                  cancelButtonTitle: "Cancel",
                  otherButtonTitles: "OK"
                )

顺便说一句，这是我得到的错误（从 Xcode 6.4 开始）：

找不到接受类型为“（标题：字符串，消息：字符串，委托：MyViewController，cancelButtonTitle：字符串，otherButtonTitles：字符串）”的参数列表的“UIAlertView”类型的初始化程序

正如其他人所提到的，如果您可以针对 iOS 8.x+，您应该迁移到 UIAlertController。要支持 iOS 7，请使用上面的代码（Swift 不支持 iOS 6）。

---

 let alertController = UIAlertController(title: "Select Photo", message: "Select atleast one photo", preferredStyle: .alert)
    let action1 = UIAlertAction(title: "From Photo", style: .default) { (action) in
        print("Default is pressed.....")
    }
    let action2 = UIAlertAction(title: "Cancel", style: .cancel) { (action) in
        print("Cancel is pressed......")
    }
    let action3 = UIAlertAction(title: "Click new", style: .default) { (action) in
        print("Destructive is pressed....")

    }
    alertController.addAction(action1)
    alertController.addAction(action2)
    alertController.addAction(action3)
    self.present(alertController, animated: true, completion: nil)

}

---

您可以使用带有 n 个按钮和相关操作的简单扩展 swift4 及更高版本

extension UIViewController {
    func popupAlert(title: String?, message: String?, actionTitles:[String?], actions:[((UIAlertAction) -> Void)?]) {
        let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
        for (index, title) in actionTitles.enumerated() {
            let action = UIAlertAction(title: title, style: .default, handler: actions[index])
            alert.addAction(action)
        }
        self.present(alert, animated: true, completion: nil)
    }
}

你可以像这样使用它，

self.popupAlert(title: "Message", message: "your message", actionTitles: ["first","second","third"], actions:[
            {action1 in
                //action for first btn click
            },
            {action2 in
                //action for second btn click
            },
            {action3 in
                //action for third btn click
            }, nil]) 

---

它不起作用的原因是您传递给函数的某些值不正确。 swift 不喜欢 Objective-C，你可以将 nil 放在类类型的参数上，没有任何限制（可能是）。参数 otherButtonTitles 被定义为非可选的，其类型在其末尾没有 (?)。所以你必须给它传递一个具体的值。

---

@IBAction func Alert(sender: UIButton) {

    var alertView:UIAlertView = UIAlertView()
    alertView.title = "Alert!"
    alertView.message = "Message"
    alertView.delegate = self
    alertView.addButtonWithTitle("OK")

    alertView.show()

}

尝试这个

---

使用此代码显示警报视图

  let alertController = UIAlertController(title: "Hello  Coders", message: "your alert message", preferredStyle: .Alert)
        let defaultAction = UIAlertAction(title: "Close Alert", style: .Default, handler: nil)
        alertController.addAction(defaultAction)

        presentViewController(alertController, animated: true, completion: nil)

参考：Swift Show Alert using UIAlertController

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在 xcode 9

let alert = UIAlertController(title: "Alert", message: "message", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Ok", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated: true, completion: nil)

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SWIFT 4：只需为 UIViewController 创建一个扩展，如下所示：

extension  UIViewController {        
    func showSuccessAlert(withTitle title: String, andMessage message:String) {
        let alert = UIAlertController(title: title, message: message,
                                  preferredStyle: UIAlertController.Style.alert)
        alert.addAction(UIAlertAction(title: "OK".localized, style:
        UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)
    }
}

现在在您的 ViewController 中，直接调用上面的函数，就好像它们是由 UIViewController 提供的一样。

    yourViewController.showSuccessAlert(withTitle: 
      "YourTitle", andMessage: "YourCustomTitle")

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或者只是这样做

        let alert = UIAlertController(title: "Alert", message: "Saved Successfully", preferredStyle: UIAlertController.Style.alert)
        alert.addAction(UIAlertAction(title: "Ok", style: UIAlertAction.Style.default, handler: nil))
        self.present(alert, animated: true, completion: nil)

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尝试这个。将波纹管代码放入按钮中。

let alert = UIAlertController(title: "Your_Title_Text", message: "Your_MSG", preferredStyle: UIAlertControllerStyle.alert)
alert.addAction(UIAlertAction(title: "Your_Text", style: UIAlertActionStyle.default, handler: nil))
self.present(alert, animated:true, completion: nil)

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这是 Swift 中一个有趣的例子：

private func presentRandomJoke() {
  if let randomJoke: String = jokesController.randomJoke() {
    let alertController: UIAlertController = UIAlertController(title:nil, message:randomJoke, preferredStyle: UIAlertControllerStyle.Alert)
    alertController.addAction(UIAlertAction(title:"Done", style:UIAlertActionStyle.Default, handler:nil))
    presentViewController(alertController, animated:true, completion:nil)
  }
}

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这是 Swift 中 AlertView 的一个非常简单的功能：

class func globalAlertYesNo(msg: String) {
        let alertView = UNAlertView(title: "Title", message: msg)

        alertView.messageAlignment = NSTextAlignment.Center
        alertView.buttonAlignment  = UNButtonAlignment.Horizontal

        alertView.addButton("Yes", action: {

            print("Yes action")

        })

        alertView.addButton("No", action: {

            print("No action")

        })

        alertView.show()

    }

您必须在使用此函数的地方将消息作为字符串传递。

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旧方式：UIAlertView

let alertView = UIAlertView(title: "Default Style", message: "A standard alert.", delegate: self, cancelButtonTitle: "Cancel", otherButtonTitles: "OK")
alertView.alertViewStyle = .Default
alertView.show()

// MARK: UIAlertViewDelegate

 func alertView(alertView: UIAlertView, clickedButtonAtIndex buttonIndex: Int) {
 switch buttonIndex {

    // ...
   }
  }

新方式：UIAlertController

let alertController = UIAlertController(title: "Default Style", message: "A standard alert.", preferredStyle: .Alert)

let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel) { (action) in
// ...
 }
 alertController.addAction(cancelAction)

 let OKAction = UIAlertAction(title: "OK", style: .Default) { (action) in
// ...
 }
 alertController.addAction(OKAction)
 self.presentViewController(alertController, animated: true) {
 // ...
}

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