Swift Type Check

expression is Type

let value: Any = 5

let isInteger = value is Int    // true: the underlying dynamic type is Int
let isString = value is String  // false: the underlying dynamic type is not String

class Base {}
class Derived: Base {}
class Unrelated {}

let instance: Any = Derived()

let check1 = instance is Derived    // true: instance is dynamically of type Derived
let check2 = instance is Base       // true: Derived inherits from Base
let check3 = instance is Unrelated  // false: Unrelated is not in the inheritance hierarchy

protocol Evaluable {}
class Node: Evaluable {}

let item: Any = Node()
let staticItem: Node = Node()

let conforms1 = item is Evaluable       // true: dynamic type conforms to Evaluable
let conforms2 = staticItem is Evaluable // true: evaluates class metadata directly

let optionalValue: Int? = 5
let anyOptional: Any = optionalValue

let check1 = optionalValue is Int // true: implicitly unwraps the Optional
let check2 = anyOptional is Int   // true: looks through both Any and Optional wrappers

let typeInstance: Any.Type = Derived.self

let isDerivedType = typeInstance is Derived.Type // true
let isBaseType = typeInstance is Base.Type       // true: Derived.Type is a subtype of Base.Type