# iOS FlutterViewController splashScreenView made nullable

> FlutterViewController splashScreenView changed from nonnull to nullable.




:::important
These breaking change docs are accurate, as of the release
under which they are published. Over time, the
workarounds described here might become inaccurate.
We don't, in general, keep these breaking change docs up
to date as of each release.

The [breaking change index file](/release/breaking-changes)
lists the docs created for each release.
:::


## Summary

The `FlutterViewController` property `splashScreenView` has
been changed from `nonnull` to `nullable`.

Old declaration of `splashScreenView`:

```objc
@property(strong, nonatomic) UIView* splashScreenView;
```

New declaration of `splashScreenView`:

```objc
@property(strong, nonatomic, nullable) UIView* splashScreenView;
```

## Context

Prior to this change, on iOS the `splashScreenView` property returned `nil`
when no splash screen view was set, and
setting the property to `nil` removed the splash screen view.
However, the `splashScreenView` API was incorrectly marked `nonnull`.
This property is most often used when transitioning to
Flutter views in iOS add-to-app scenarios.

## Description of change

While it was possible in Objective-C to work around the
incorrect `nonnull` annotation by setting `splashScreenView` to
a `nil` `UIView`, in Swift this caused a compilation error:

```plaintext
error build: Value of optional type 'UIView?' must be unwrapped to a value of type 'UIView'
```

[PR #34743][] updates the property attribute to `nullable`.
It can return `nil` and can be set to `nil` to
remove the view in both Objective-C and Swift.

## Migration guide

If `splashScreenView` is stored in a `UIView` variable in Swift,
update to an optional type `UIView?`.

Code before migration:

```swift
  var splashScreenView = UIView()
  var flutterEngine = FlutterEngine(name: "my flutter engine")
  let flutterViewController = FlutterViewController(engine: flutterEngine, nibName: nil, bundle: nil)
  splashScreenView = flutterViewController.splashScreenView // compilation error: Value of optional type 'UIView?' must be unwrapped to a value of type 'UIView'
```

Code after migration:

```swift
  var splashScreenView : UIView? = UIView()
  var flutterEngine = FlutterEngine(name: "my flutter engine")
  let flutterViewController = FlutterViewController(engine: flutterEngine, nibName: nil, bundle: nil)
  let splashScreenView = flutterViewController.splashScreenView // compiles successfully
  if let splashScreenView = splashScreenView {
  }
```

## Timeline

In stable release: 3.7

## References

Relevant PR:

* [Make splashScreenView of FlutterViewController nullable][]

[Make splashScreenView of FlutterViewController nullable]: https://github.com/flutter/engine/pull/34743
[PR #34743]: https://github.com/flutter/engine/pull/34743