Persisting a PKDrawing to iCloud

Question

Created Jun ’20

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I have an App in which I am using NSPersistentCloudKitContainer to store user's drawings, and to have them in sync across multiple devices.

To store the drawings, I am using a "Binary Data" attribute in my Core Data entity. In this attribute I am saving the data representation of the drawing by using this API https://developer.apple.com/documentation/pencilkit/pkdrawing/3281878-datarepresentation

I have observed that for some drawings this data representation consumes a huge amount of data, and that generates synchronisation problems among devices.

Is there a better approach to persist PKDrawings without this problem?

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Answer 1

OP

Apple

Jun ’20

CloudKit automatically turns your data into a CKAsset when it gets too big. I suppose the upload speed of your device's internet connection is the bottleneck here and there's not much we can do about it. If a drawing doesn't need to be edited anymore, it's probably best to turn it into an image and remove the drawing's data representation from your model object.

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Answer 2

Frameworks Engineer OP

Apple

Jun ’20

You probably want to explore a different serialization approach for PKDrawing than a transformable or binary data property.

Breaking the drawing up in to strokes for example, or a set of strokes modeled as a contribution to the drawing, would significantly reduce the serialization and sync overhead for large drawings.

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