What is the @SceneStorage property wrapper?
Updated for Xcode 12.5
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(StackNavigationViewStyle())
}
}Note: I’ve used StackNavigationViewStyle there because it forces the iPad to allocate all the space to our text editor.
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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