Swift完成UIAlertController的调用

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。

我们先来看一下Apple的UIAlertController的文档：

import Foundation
import 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)

var alert: UIAlertController = UIAlertController(title: nil, message:"test", preferredStyle: UIAlertControllerStyle.ActionSheet)

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")
                })

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)

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")
                    }
                }
            ))

Tips：

如果style是cancel 那么字体会变粗；如果是destructive,字体会显示红色。