iOS8中的UIAlertView和UIActionSheet已经都被UIAlertViewController代替了，所以，本篇blog就来探讨下如何用swift生成提示框，
Swift完成UIAlertController的调用
。我们先来看一下Apple的UIAlertController的文档：
import Foundationimport UIKit//// UIAlertController.h// UIKit//// Copyright (c) 2014 Apple Inc. All rights reserved.//@availability(iOS, introduced=8.0)enum UIAlertActionStyle. Int { case Default case Cancel case Destructive}@availability(iOS, introduced=8.0)enum UIAlertControllerStyle. Int { case ActionSheet case Alert}@availability(iOS, introduced=8.0)class UIAlertAction : NSObject, NSCopying { convenience init(title: String, style. UIAlertActionStyle, handler: ((UIAlertAction!) ->Void)!) var title: String { get } var style. UIAlertActionStyle. { get } var enabled: Bool}@availability(iOS, introduced=8.0)class UIAlertController : UIViewController { convenience init(title: String?, message: String?, preferredStyle. UIAlertControllerStyle) func addAction(action: UIAlertAction) var actions: [AnyObject] { get } func addTextFieldWithConfigurationHandler(configurationHandler: ((UITextField!) ->Void)!) var textFields: [AnyObject]? { get } var title: String? var message: String? var preferredStyle. UIAlertControllerStyle. { get }}我们可以看到UIAlertController的style有两个，一个是ActionSheet，一个是Alert，而AlertActionStyle有3个： Default，Cancel, Destructive；所以我们新建Alert时可以这样：
var alert: UIAlertController = UIAlertController(title:nil, message:"您输入的电话号码有误，请检查后重新输入", preferredStyle.:UIAlertControllerStyle.Alert)
或者
var alert: UIAlertController = UIAlertController(title: nil, message:"test", preferredStyle. UIAlertControllerStyle.ActionSheet)接下来我们来给Alert添加action，从文档中可以看到AlertAction有init函数，
我们来新建3个actions
var saveAction = UIAlertAction(title: "Save", style. .Default, handler:{ (alerts: UIAlertAction!) ->Void in println("File saved") }) var deleteAction = UIAlertAction(title: "Delete", style. .Default, handler:{ (alerts: UIAlertAction!) ->Void in println("File delete") }) var cancelAction = UIAlertAction(title: "Cancel", style. .Cancel, handler:{ (alerts: UIAlertAction!) ->Void in println("Cancelled") })注意到handler中用到了一个closure然后给我们的alertcontroller添加actions，并把它显示出来
alert.addAction(saveAction) alert.addAction(deleteAction) alert.addAction(cancelAction) self.presentViewController(alert, animated: true, completion: nil)
我们也可以这样添加action
alert.addAction(UIAlertAction(title: "确定", style. .Destructive, handler: { action in switch action.style{ case .Default: println("ok") case .Cancel: println("cancel") case .Destructive: println("Destructive") } } ))接下来运行一下看看我们的alertController是什么样子的吧，电脑资料
《Swift完成UIAlertController的调用》(https://www.unjs.com)。Tips：
如果style是cancel 那么字体会变粗；如果是destructive,字体会显示红色。