[swift] is & as、Any & AnyObject

is & as

是用于swift 的类型检测

用简单的话来说就是：

class FatherClass {
    var name: String
    init(name: String) {
        self.name = name
    }
}

class SubClassA: FatherClass {
    var proa: String
    init(name: String,proa: String) {
        self.proa = proa
        super.init(name: Name)
    }
}

class SubClassB: FatherClass {
    var proB: String
    init(name: String,proB: String) {
        self.proB = proB
        super.init(name: Name)
    }
}

let Dic = [
    SubClassA(name: "One",proa: "A pro one"),SubClassA(name: "Two",proa: "A pro two"),SubClassB(name: "Three",proB: "B pro one"),SubClassA(name: "Four",proa: "A pro three"),SubClassA(name: "Five",proa: "A pro four")
]

for item in Dic {
    if item is SubClassA {
        print("\(item.Name) is SubClassA")
    } else if item is SubClassB {
        print("\(item.Name) is SubClassB")
    }
}

//One is SubClassA
//Two is SubClassA
//Three is SubClassB
//Four is SubClassA
//Five is SubClassA

for item in Dic {
    if let subClassA = item as? SubClassA {
        print("SubClassA: '\(subClassA.Name)',proa. \(subClassA.proa)")
    } else if let subClassB = item as? SubClassB {
        print("SubClassB: '\(subClassB.Name)',proB. \(subClassB.proB)")
    }
}

//SubClassA: 'One',proa. A pro one
//SubClassA: 'Two',proa. A pro two
//SubClassB: 'Three',proB. B pro one
//SubClassA: 'Four',proa. A pro three
//SubClassA: 'Five',proa. A pro four

Any & AnyObject

两种不确定类型

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(SubClassA(name: "Six",proa: "A pro five"))
things.append(SubClassB(name: "Seven",proB: "B pro two"))

for thing in things {
    switch thing {
    case 0 as Int:
        print("zero as an Int")
    case 0 as Double:
        print("zero as a Double")
    case let someInt as Int:
        print("an Integer value of \(someint)")
    case let someDouble as Double where someDouble > 0:
        print("a positive double value of \(someDoublE)")
    case is Double:
        print("some other double value that I don't want to print")
    case let someString as String:
        print("a String value of \"\(someString)\"")
    case let (x,y) as (Double,DoublE):
        print("an (x,y) point at \(X),\(y)")
    case let subClassA as SubClassA:
        print("a subclass called '\(subClassA.Name)',proa. \(subClassA.proa)")
    case let subClassB as SubClassB:
        print("a subclass called '\(subClassB.Name)',proB. \(subClassB.proB)")
    default:
        print("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 subclass called 'Six',proa. A pro five
//a subclass called 'Seven',proB. B pro two