macOS Compatibility

[duncangroenewald]

Description

This library looks interesting but I don't see any mention of compatibility with AppKit, particularly for observing changes and updating AppKit user interface elements.

The examples provided appear to be using UIKit APIs such as NSDiffableDataSourceSnapshot.

Perhaps a simple example of updating NSTableView or NSOutlineView from within NSViewController could be provided.

Checklist

• I have determined whether this bug is also reproducible in a vanilla SwiftUI project.
• I have determined whether this bug is also reproducible in a vanilla GRDB project.
• If possible, I've reproduced the issue using the main branch of this package.
• This issue hasn't been addressed in an existing GitHub issue or discussion.

Expected behavior

Updated AppKit code example

Actual behavior

Updated AppKit code example

Reproducing project

Updated AppKit code example

SQLiteData version information

No response

Sharing version information

No response

GRDB version information

No response

Destination operating system

No response

Xcode version information

No response

Swift Compiler version information

[mbrandonw]

Hi @duncangroenewald, while we don't have an AppKit example, we do have a UIKit example that shows how to power a UICollectionView from a @FetchAll:

sqlite-data/Examples/CaseStudies/UIKitDemo.swift

Lines 76 to 82 in ba32f0b

	observe { [weak self] in
	guard let self else { return }
	var snapshot = NSDiffableDataSourceSnapshot<Section, Fact>()
	snapshot.appendSections([.facts])
	snapshot.appendItems(facts, toSection: .facts)
	dataSource.apply(snapshot, animatingDifferences: true)
	}

In short, you use observe with a trailing closure, and in that closure you are free to access any state that is modeled as @FetchAll, @FetchOne or @Fetch (and more generally, anything that is @Observable). Then when that state changes the trailing closure will be invoked again and that gives you a chance to update your view/controller. In the case of the above code we recompute the data source and apply the snapshot to the collection view.

If you have any concrete questions about integrating with AppKit we will be happy to look into it more and discuss with you.

Also, since this isn't an issue with the library I am going to convert it to a discussion. Please feel free to continue the conversation over there!

[duncangroenewald]

Typically one would bind the items array to an NSArrayController content property and any changes to the items array would trigger updates via the NSArrayController. In addition one would bind the individual items properties to AppKit UI elements such as text fields. Any item property updates would trigger UI updates.

It is not clear whether this would work or whether some specific logic is required in the observe callback to trigger the list updates as well as updates to the individual item property fields.

[mbrandonw]

I'm not super familiar with NSArrayController but my understanding of it is that it is heavily based in the Objective-C/KVO world and as such will not play nicely with SQLiteData since it is based on value types. So you would need to work directly with NSTableViewDataSource and NSTableViewDelegate, and then in the observe { … } you would simply update the data source with the new data and invoke reloadData() on the table view.

[duncangroenewald]

Ah yes - I guess one could also invoke willChangeValueForKey(), didChangeValueForKey() on the items array from the observe callback.

Probably more of an issue is whether SQLiteData model objects have to be structs or can they be NSObjects. Unless I am mistaken structs won't play nice either.

[mbrandonw]

The @Table macro requires structs. It cannot be used with classes.

[duncangroenewald]

Thought that might be the case. thanks.

[rcarver]

Just to clarify for anyone else coming to this discussion, SQLiteData works wonderfully in a modern macOS app. Mine is a mix of SwiftUI and AppKit, uses TCA and observation heavily including a large, complex NSCollectionView

[duncangroenewald]

I can put something together based on NSObject, NSArrayController, NSTreeController, NSOutlineView - the scaffolding is pretty depended on these unless you don't use bindings - which I think means coding a lot of observers.

Someone else will have to figure out how to replace these with something that works with structs - I would think you have no choice but to use SwiftUI for this - which seems to have some pretty basic limitations in the macOS world.

It almost seems that it might be easier to make SQLiteData work with NSObject model objects rather than structs.

To me there is a fundamental problem with using structs for persistent objects because in an application such persistent objects should only have one instance and any change to that instance should be visible across the application. Struts doesnt seem to lend itself to that because copies get made all the time.

Curious as to how this issue gets addressed with SQLiteData.

[duncangroenewald]

Here is a very simple example of a hierarchy - Master - Detail. Download from the link below.

https://duncangroenewald.com/files/Software/sqlite-data-test.zip

[mbrandonw]

Hi @duncangroenewald, great thanks for that! That helps us understand what it is you're looking for.

It almost seems that it might be easier to make SQLiteData work with NSObject model objects rather than structs.

Sorry but that's not likely to happen. One of the main points of SQLiteData is to allow one to model their types with structs instead of classes.

To me there is a fundamental problem with using structs for persistent objects because in an application such persistent objects should only have one instance and any change to that instance should be visible across the application. Struts doesnt seem to lend itself to that because copies get made all the time.

References are certainly the SwiftData/Core Data approach to this problem, but it's not the only way to attack the problem.

[rcarver]

That's cool to see, I've never worked with those APIs. I'll take a pass at creating a similar demo using SQLiteData and Observation - I'm pretty sure an NSOutlineView is in my app's future so this is great way to get familiar.

[duncangroenewald]

Download the latest version of the sample project - I fixed the detail bindings in the latest version using NSObjectController