Best practices for preserving data between app launches for SwiftUI

Question

Created Jun ’20

Replies 4

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Participants 3

I understand how to use Codable to serialize data, how to read and write to UserDefaults, and that SwiftUI provides events like "sceneWillResignActive" and "sceneWillEnterForeground".

What I am missing is how to tie all of this together - what are the best practices for preserving data between app launches for SwiftUI?

It feels like I should capture important data values and write them during the Scene's lifecycle events. Can someone highlight an article or post that clarifies this?

Thank you.

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Answer 1

Hunter OP

Jul ’20

Take a look at @SceneStorage.

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Answer 2

Macphisto OP

Jul ’20

There are some good references online to the SceneStorage addition to SwiftUI, and it seems a great solution for basic scene restoration. There are some significant caveats that imply we will must have a mastery of the app's lifecycle to save and restore application data. Coming from UIKit we would tap into Appdelegate events... I am unclear what is the right way within this framework.

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Answer 3

duncang OP

Jul ’20

Nevermind preserving between launches - what about preserving state when switching between views - simple things like a list view forgets what item was selected and what its scroll position was.

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Answer 4

Macphisto OP

Jul ’20

@duncang I think SceneStorage is what you want

For anyone else reading this thread, I am going to go with saving context in sceneDidEnterBackground and loading context in scene.willConnectTo

I feel like I should also be hooking into sceneWillEnterForeground but so far in my testing I haven't needed to.

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