[Swift] Any VS AnyObject

当明白 @UIApplicationMain  的内涵段子后，又发现一个神奇的东西

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {                // Override point for customization after application launch.        return true    }

出现了 AnyObject , 这是什么东西，[NSObject:AnyObject] 又是什么东西，感觉怪怪的

完全不适应呀，和之前的beta 版对比会发现社么呢？？？

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {                // Override point for customization after application launch.        return true    }

原来是用[NSObject:AnyObject] 来替换 NSDictionary 的，那又是为什么呢，中括号又是干什么的？，“？”又是干嘛的

瞬间疑问更多了，首先是看到官方的解释

哦，原来 AnyObject 是无类型的实例呀，准确来说 Any 是无类型的任何东西的实例，可以使基本数据类型、方法、闭包等

是不是想到了万能的 Id 指针、void 这些东西，而且官方还让在知道类型的时候，不用他们俩，必要时才推荐用。。。

哦，或许会明白 Any、AnyObject 这俩的概念了 [NSObject:AnyObject] 是啥东西，和 NSDictionary 有啥关系呢？

第一反应就是，前者可能是 后者的一种形式，查阅资料才明白，原来是。。。 XXX

字典的声明有这么多：

A： var creditDictionary = Dictionary<String,Int>()  

B： var shorthandDictionary = [String:Int]()  

C： var emptyDictionary = [:] (空字典也可以这样 ~~ OMG ~~)

这样我们就可以简单的理解 [] 就是取 实例的对应的类，然后我们也会见到类似数组的声明

A： var intArray = Array<Int>()  

B： var shorthandArray = [Int]()

C： shorthandArray = [] (这样够空的了。。)

更多关于Swift 中的 NSArray 、NSDictionary 详见喵神：

http://onevcat.com/2014/06/walk-in-swift/

那么对问题有了了解后，？ 是干嘛的呢，拆包呀，还有！ 呢

详情解释见 代码手工艺人 解释：

http://www.cocoachina.com/swift/20140605/8687.html

最后贴个官方的相关代码吧

AnyObject：

let someObjects: [AnyObject] = [    Movie(name: "2001: A Space Odyssey", director: "Stanley Kubrick"),    Movie(name: "Moon", director: "Duncan Jones"),    Movie(name: "Alien", director: "Ridley Scott")]

<pre name="code" class="html">for object in someObjects {    let movie = object as Movie    println("Movie: '\(movie.name)', dir. \(movie.director)")}// Movie: '2001: A Space Odyssey', dir. Stanley Kubrick// Movie: 'Moon', dir. Duncan Jones// Movie: 'Alien', dir. Ridley Scott

view plain copy to clipboard print ?

1. for movie in someObjects as [Movie] {    println("Movie: '\(movie.name)', dir. \(movie.director)")}// Movie: '2001: A Space Odyssey', dir. Stanley Kubrick// Movie: 'Moon', dir. Duncan Jones// Movie: 'Alien', dir. Ridley Scott  

Any：

var things = [Any]()things.append(0)things.append(0.0)things.append(42)things.append(3.14159)things.append("hello")things.append((3.0, 5.0))things.append(Movie(name: "Ghostbusters", director: "Ivan Reitman"))things.append({ (name: String) -> String in "Hello, \(name)" })

for thing in things {    switch thing {    case 0 as Int:        println("zero as an Int")    case 0 as Double:        println("zero as a Double")    case let someInt as Int:        println("an integer value of \(someInt)")    case let someDouble as Double where someDouble > 0:        println("a positive double value of \(someDouble)")    case is Double:        println("some other double value that I don't want to print")    case let someString as String:        println("a string value of \"\(someString)\"")    case let (x, y) as (Double, Double):        println("an (x, y) point at \(x), \(y)")    case let movie as Movie:        println("a movie called '\(movie.name)', dir. \(movie.director)")    case let stringConverter as String -> String:        println(stringConverter("Michael"))    default:        println("something else")    }}

for thing in things {    switch thing {    case 0 as Int:        println("zero as an Int")    case 0 as Double:        println("zero as a Double")    case let someInt as Int:        println("an integer value of \(someInt)")    case let someDouble as Double where someDouble > 0:        println("a positive double value of \(someDouble)")    case is Double:        println("some other double value that I don't want to print")    case let someString as String:        println("a string value of \"\(someString)\"")    case let (x, y) as (Double, Double):        println("an (x, y) point at \(x), \(y)")    case let movie as Movie:        println("a movie called '\(movie.name)', dir. \(movie.director)")    case let stringConverter as String -> String:        println(stringConverter("Michael"))    default:        println("something else")    }}

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1. // zero as an Int// zero as a Double// an integer value of 42// a positive double value of 3.14159// a string value of "hello"// an (x, y) point at 3.0, 5.0// a movie called 'Ghostbusters', dir. Ivan Reitman// Hello, Michael  

其他相关

喵神贴

http://swifter.tips/any-anyobject/

官方资料

https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/TypeCasting.html