[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 =  shorthandDictionary = [:]
(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

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")
    }
}

<pre name="code" class="html">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")
    }
}

// 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