---
title: "willMove(toParent:)"
framework: uikit
role: symbol
role_heading: Instance Method
path: "uikit/uiviewcontroller/willmove(toparent:)"
---

# willMove(toParent:)

Called just before the view controller is added or removed from a container view controller.

## Declaration

```swift
func willMove(toParent parent: UIViewController?)
```

## Parameters

- `parent`: The parent view controller, or nil if there is no parent.

## Mentioned in

Creating a custom container view controller

## Discussion

Discussion Your view controller can override this method when it needs to know that it has been added to a container. If you are implementing your own container view controller, it must call the willMove(toParent:) method of the child view controller before calling the removeFromParent() method, passing in a parent value of nil. When your custom container calls the addChild(_:) method, it automatically calls the willMove(toParent:) method of the view controller to be added as a child before adding it.

## See Also

### Responding to containment events

- [didMove(toParent:)](uikit/uiviewcontroller/didmove(toparent:).md)