如何在Swift中获取变量“ Any？”的实型

Question

I get property list from Mirror.children, it returns (label: String?, value: Any). How can i get every value's real type.

var a: Int = 1
var b: Int? = nil
var c: Any?

c = a
getType(c) -> "Int"

c = b
getType(c) -> "Optional<Int>"

Answer 1

您可以看一下c.dynamicType 。

Answer 2

Metatype Type

A metatype type refers to the type of any type, including class types, structure types, enumeration types, and protocol types.

The metatype of a class, structure, or enumeration type is the name of that type followed by .Type. The metatype of a protocol type—not the concrete type that conforms to the protocol at runtime—is the name of that protocol followed by .Protocol. For example, the metatype of the class type SomeClass is SomeClass.Type and the metatype of the protocol SomeProtocol is SomeProtocol.Protocol.

You can use the postfix self expression to access a type as a value. For example, SomeClass.self returns SomeClass itself, not an instance of SomeClass. And SomeProtocol.self returns SomeProtocol itself, not an instance of a type that conforms to SomeProtocol at runtime. You can use a dynamicType expression with an instance of a type to access that instance's dynamic, runtime type as a value, as the following example shows:

class SomeBaseClass {
    class func printClassName() {
        print("SomeBaseClass")
    }
}
class SomeSubClass: SomeBaseClass {
    override class func printClassName() {
        print("SomeSubClass")
    }
}
let someInstance: SomeBaseClass = SomeSubClass()
// The compile-time type of someInstance is SomeBaseClass,
// and the runtime type of someInstance is SomeBaseClass
someInstance.dynamicType.printClassName()
// prints "SomeSubClass

Use the identity operators (=== and !==) to test whether an instance's runtime type is the same as its compile-time type.

if someInstance.dynamicType === someInstance.self {
    print("The dynamic type of someInstance is SomeBaseCass")
} else {
    print("The dynamic type of someInstance isn't SomeBaseClass")
}
// prints "The dynamic type of someInstance isn't SomeBaseClass"

Use an initializer expression to construct an instance of a type from that type's metatype value. For class instances, the initializer that's called must be marked with the required keyword or the entire class marked with the final keyword.

class AnotherSubClass: SomeBaseClass {
    let string: String
    required init(string: String) {
        self.string = string
    }
    override class func printClassName() {
        print("AnotherSubClass")
    }
}
let metatype: AnotherSubClass.Type = AnotherSubClass.self
let anotherInstance = metatype.init(string: "some string")