---
title: Handling Dynamically Typed Methods and Objects in Swift
framework: swift
role: article
role_heading: Article
path: swift/handling-dynamically-typed-methods-and-objects-in-swift
---

# Handling Dynamically Typed Methods and Objects in Swift

Cast instances of the Objective-C id type to a specific Swift type.

## Overview

Overview In Objective-C, the id type represents objects that are instances of any Objective-C class. The id type is instead imported by Swift as the Any type. When you pass a Swift instance to an Objective-C API, it’s bridged as an id parameter so that it’s usable in the API as an Objective-C object. When id values are imported into Swift as Any, the runtime automatically handles bridging back to either class references or value types. var x: Any = "hello" as String x as? String   // String with value "hello" x as? NSString // NSString with value "hello"

x = "goodbye" as NSString x as? String   // String with value "goodbye" x as? NSString // NSString with value "goodbye" Downcast Objects to Call Methods and Access Properties When you work with objects of type Any where you know the underlying type, it’s often useful to downcast those objects to the underlying type. However, because the Any type can refer to any type, a downcast to a more specific type isn’t guaranteed by the compiler to succeed. You can use the conditional type cast operator (as?), which returns an optional value of the type you are trying to downcast to: let userDefaults = UserDefaults.standard let lastRefreshDate = userDefaults.object(forKey: "LastRefreshDate") // lastRefreshDate is of type Any? if let date = lastRefreshDate as? Date {     print("\(date.timeIntervalSinceReferenceDate)") } If you’re completely certain about the type of the object, you can use the forced downcast operator (as!) instead. let myDate = lastRefreshDate as! Date let timeInterval = myDate.timeIntervalSinceReferenceDate However, if a forced downcast fails, a runtime error is triggered: let myDate = lastRefreshDate as! String // Error

## See Also

### Language Interoperability with Objective-C and C

- [Objective-C and C Code Customization](swift/objective-c-and-c-code-customization.md)
- [Migrating Your Objective-C Code to Swift](swift/migrating-your-objective-c-code-to-swift.md)
- [Cocoa Design Patterns](swift/cocoa-design-patterns.md)
- [Using Objective-C Runtime Features in Swift](swift/using-objective-c-runtime-features-in-swift.md)
- [Imported C and Objective-C APIs](swift/imported-c-and-objective-c-apis.md)
- [Calling Objective-C APIs Asynchronously](swift/calling-objective-c-apis-asynchronously.md)