[Swift] Any VS AnyObject

深碍√TFBOYSˉ_ 2022-08-06 05:26 97阅读 0赞

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

![Center][]

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/  
][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][Link 1]**解释：**

[http://www.cocoachina.com/swift/20140605/8687.html][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")
        }
    }

// 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/  
][http_swifter.tips_any-anyobject_]**

**官方资料**

**[https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift\_Programming\_Language/TypeCasting.html][https_developer.apple.com_library_ios_documentation_Swift_Conceptual_Swift_Programming_Language_TypeCasting.html]**

[Center]: /images/20220806/d216f61f11184aec8e245b71c91ca457.png
[http_onevcat.com_2014_06_walk-in-swift_]: http://onevcat.com/2014/06/walk-in-swift/
[Link 1]: http://joeyio.com/ios/2014/06/04/swift---/
[http_www.cocoachina.com_swift_20140605_8687.html]: http://www.cocoachina.com/swift/20140605/8687.html
[http_swifter.tips_any-anyobject_]: http://swifter.tips/any-anyobject/
[https_developer.apple.com_library_ios_documentation_Swift_Conceptual_Swift_Programming_Language_TypeCasting.html]: https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/TypeCasting.html