SWIFT 4:简单地为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)
    }
}

现在在你的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")

Swift 5上的SwiftUI。x和Xcode 11.x

import SwiftUI

struct ContentView: View {

    @State private var isShowingAlert = false

    var body: some View {
        VStack {
            Button("A Button") {

                self.isShowingAlert.toggle()
            }
            .alert(isPresented: $isShowingAlert) { () -> Alert in
                Alert(
                    title: Text("Alert"),
                    message: Text("This is an alert"),
                    dismissButton:
                        .default(
                            Text("OK"),
                            action: {
                                print("Dismissing alert")
                            }
                        )
                )
            }

        }
        .padding()
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

@IBAction func Alert(sender: UIButton) {

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

    alertView.show()

}

试试这个

下面是警报视图和动作表的可重用代码，只需写一行在应用程序的任何地方显示警报

class AlertView{

    static func show(title:String? = nil,message:String?,preferredStyle: UIAlertControllerStyle = .alert,buttons:[String] = ["Ok"],completionHandler:@escaping (String)->Void){
        let alert = UIAlertController(title: title, message: message, preferredStyle: preferredStyle)

        for button in buttons{

            var style = UIAlertActionStyle.default
            let buttonText = button.lowercased().replacingOccurrences(of: " ", with: "")
            if buttonText == "cancel"{
                style = .cancel
            }
            let action = UIAlertAction(title: button, style: style) { (_) in
                completionHandler(button)
            }
            alert.addAction(action)
        }

        DispatchQueue.main.async {
            if let app = UIApplication.shared.delegate as? AppDelegate, let rootViewController = app.window?.rootViewController {
                rootViewController.present(alert, animated: true, completion: nil)
            }

        }
    }
}

用法:

class ViewController: UIViewController {

    override func viewWillAppear(_ animated: Bool) {
        AlertView.show(title: "Alert", message: "Are you sure ?", preferredStyle: .alert, buttons: ["Yes","No"]) { (button) in
            print(button)
        }
    }

}

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")
  }))

}

完成两个按钮确定&取消

iOS 13 Xcode 11+ Swift 5。X

UIAlertController现在可以提供警报以及动作表

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，当点击警报视图时，所有操作按钮的基本属性都是关闭警报视图。style参数只是用来决定文本的颜色(以及按钮应该出现的默认顺序，这些ofc可以改变)

示例处理程序函数可以是

func handler(_ action: UIAlertAction) { 

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

}

作为旁注，我想说的是，与其创建3个不同的处理程序，你可以只创建1个处理程序，并以上面所示的方式跟踪到引发它的元素 我们也可以检查警报。我们可以有多个。default样式的动作，我不建议这样做

动作表

解释是类似的，因为这里的主要区别是提醒会打断用户，而在iPhone中，操作表从底部滑动，在iPad中以弹出窗口的形式出现

操作表的目的是指导用户根据当前状态决定操作。所以你必须像对待十字路口一样对待动作表单!通常没有消息，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)

上面的代码将在iPhone上工作，但在iPad上运行时会崩溃，因为UIPopoverPresentationController将负责警报，它不会在那个时候引用任何东西。因此，为了避免这种情况，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
 }

同样，如果iPad点击弹窗之外的任何地方，它将被解散，.cancel操作按钮的完成处理程序将被调用。

也就是说，如果你有任何疑问，请在下方评论