What is the @SceneStorage property wrapper?
Updated for Xcode 14.0 beta 1
New in iOS 14
If you want to save unique data for each of your screens, you should use SwiftUI’s @SceneStorage property wrapper. This works a bit like @AppStorage in that you provide it with a name to save things plus a default value, but rather than working with UserDefaults it instead gets used for state restoration – and it even works great with the kinds of complex multi-scene set ups we see so often in iPadOS.
For example, if you have a text editor and want to store what the user was typing, you should use this kind of code:
struct ContentView: View {
@SceneStorage("text") var text = ""
var body: some View {
NavigationView {
TextEditor(text: $text)
}
.navigationViewStyle(.stack)
}
}Note: I’ve used .stack there because it forces the iPad to allocate all the space to our text editor. If you’re using Xcode 12, you need to use StackNavigationViewStyle to get the same result.
Because that uses @SceneStorage, SwiftUI will automatically make sure that each scene instance has its own copy of the text – if you run the app side by side both will save and restore their data correctly.
Now, before you use @SceneStorage there are some important warnings from Apple:
- Don’t save lots of data; save just what you need for state restoration.
- Never store sensitive data in scene storage, because it isn’t secure.
- If the user goes to the app switcher and destroys your app, the scene storage is also destroyed.
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