Hello there,
I'm using a combination of UIDocumentBrowserViewController + UIManagedDocument to manage documents, store and sync them with iCloud. Right now I'm trying to add support for thumbnails (custom type) using QuickLookThumbnailing framework.
In a subclass of QLThumbnailProvider when trying to open the UIManagedDocument, Xcode returns an error from within thumbnail target:
[error]addPersistentStoreWithType:configuration:URL:options:error: returned error NSCocoaErrorDomain (513)
Also UIManagedDocument itself throws an error
Error Domain=NSCocoaErrorDomain Code=513 "The file couldn’t be saved because you don’t have permission.".
The cocoa error 513 is about no writing permissions, but I'm not sure what exactly it's tried to be written. In the thumbnail extension I just init the document with the URL that system send via the system method. Also I do not change anything in the document explicitly.
I'm not sure what I'm missing, I took a look over the "Particles" example from Apple engineers, but they are using UIDocumentBrowserViewController and plain UIDocument which works great.