For network volumes where volumeUUIDStringKey is nil, is there any other stable volume/share identifier suitable for namespacing file IDs? More generally, what should I use as the volume identity component when persisting file identifiers for network files? If volumeSupportsPersistentIDsKey == true on a network volume, can fileIdentifierKey / systemFileNumber be expected to survive unmount/remount, reconnect, and server restart? Does fileIdentifierKey on network volumes represent the same kind of filesystem identity as it does on local/removable volumes? Thanks!

What does volumeSupportsPersistentIDsKey represent and guarantee on macOS? Is it specifically about persistent filesystem object IDs such as fileIdentifierKey / inode / systemFileNumber, or can it refer to other kinds of persistent IDs? For which common volume/filesystem cases would this property be false, and what should I fall back to as file identity in those cases? Thanks!

I’m building a macOS app that displays a large grid of image thumbnails similar to Photos. What is the recommended way to determine whether a file is locally available/downloaded without making a blocking call to the filesystem for every thumbnail? Thanks!

I’m building a macOS app that stores file URLs/bookmarks and displays file locations in the UI. For files in iCloud Drive, I want to show a user-friendly path such as: iCloud Drive / My Folder / File.jpg rather than an internal filesystem path. What is the recommended way to display iCloud Drive paths in a way that matches what users see in Finder? Thanks!

Is there any way to get notified in macOS when the iCloud Drive becomes online/offline so that I can update the UI in my app to reflect that state? Thanks!

Hi, In the iOS13 and macOS Catalina release notes it says: Metal CIKernel instances now support arguments with arbitrarily structured data. I've been trying to use this functionality in a CIKernel with mixed results. I'm particularly interested in passing data in the form of a dynamically sized array. It seems to work up to a certain size. Beyond the threshold excessive data is discarded and the kernel becomes unstable. I assume there is some kind of memory alignment issue going on, but I've tried various types in my array and always get a similar result. I have not found any documentation or sample code regarding this. It would be great to know how this is intended to work and what the limitations are. In the forums there are two similar unanswered questions about data arguments, so I'm sure there are a few out there with similar issues. Thanks! Michael

Hi, Introducing Swift Concurrency to my Metal app has been a bit challenging as Swift Concurrency is limited by the cooperative thread pool. GPU work is obviously not CPU bound and can block forward moving progress, especially when using waitUntilCompleted on the command buffer. For concurrent render work this has the potential of under utilizing the CPU and even creating dead locks. My question is, what is the Metal's teams general recommendation when it comes to concurrency? It seems to me that Dispatch or OperationQueues are still the preferred way for Metal bound tasks in order to gain maximum performance? To integrate with Swift Concurrency my idea is to use continuations that kick off render jobs via Dispatch or Queues? Would this be the best solution to bridge async tasks with Metal work? Thanks!

Hi, I'm having difficulties figuring out how I can reliably detect if the macOS system PHPhotoLibrary is available. If I place the system Photo Library on an external drive and then eject it, other apps on startup, such as Photos, will tell me that the library isn't available. How can I replicate this behavior? The only API I can find for this detection on startup is "PHPhotoLibrary.shared().unavailabilityReason". However this always returns nil. Another strange behavior is if I register a PHPhotoLibraryAvailabilityObserver class on startup when the library is available and then eject the drive, I do get a notification via photoLibraryDidBecomeUnavailable, but then directly after the call the app is terminated. This prevents the app to perform any kind of graceful termination. Is this the expected behavior? It would make sense that it's up to the developer to decide what happens if the library becomes unavailable. Thanks

Hi, When using Swift Concurrency blocking tasks like file I/O, GPU work and networking can prevent forward moving progress and have the potential to exhaust the cooperative thread pool and under utilize the CPU. It's been recommended to offload these tasks from the cooperative thread pool. Is my understanding correct that the preferred way to do this is by creating async tasks via Dispatch or OperationQueue? And combining these with Continuations if a return value from the task is required? Or should I always be using Continuations in combination with Dispatch/OperationQueue? There are also Executors but the documentation seems a bit limited on how to use these. The new TaskExecutor is also only available on the latest beta's. My question is basically what is the recommend way to offload a task? Thanks!