---
title: "objc_allocateClassPair(_:_:_:)"
framework: Objective-C Runtime
role: symbol
role_heading: Function
platforms: [iOS 2.0+, iPadOS 2.0+, Mac Catalyst 13.1+, macOS 10.5+, tvOS 9.0+, visionOS 1.0+, watchOS 1.0+]
path: "objectivec/objc_allocateclasspair(_:_:_:)"
---

# objc_allocateClassPair(_:_:_:)

Creates a new class and metaclass.

## Declaration

```swift
func objc_allocateClassPair(_ superclass: AnyClass?, _ name: UnsafePointer<CChar>, _ extraBytes: Int) -> AnyClass?
```

## Parameters

- `superclass`: The class to use as the new class’s superclass, or Nil to create a new root class.
- `name`: The string to use as the new class’s name. The string will be copied.
- `extraBytes`: The number of bytes to allocate for indexed ivars at the end of the class and metaclass objects. This should usually be 0.

## Return Value

Return Value The new class, or Nil if the class could not be created (for example, the desired name is already in use).

## Discussion

Discussion You can get a pointer to the new metaclass by calling object_getClass(newClass). To create a new class, start by calling objc_allocateClassPair(_:_:_:). Then set the class’s attributes with functions like class_addMethod(_:_:_:_:) and class_addIvar(_:_:_:_:_:). When you are done building the class, call objc_registerClassPair(_:). The new class is now ready for use. Instance methods and instance variables should be added to the class itself. Class methods should be added to the metaclass.

## See Also

### Adding Classes

- [objc_disposeClassPair(_:)](objectivec/objc_disposeclasspair(_:).md)
- [objc_registerClassPair(_:)](objectivec/objc_registerclasspair(_:).md)
- [objc_duplicateClass(_:_:_:)](objectivec/objc_duplicateclass(_:_:_:).md)