TopShelf example not working since tvOS 13.4

[tmm1]

In tvOS 13.4+ and 14.0 Beta, there are much stricter memory limits on top shelf extensions. The example seems to use a lot of memory and gets killed, but that can be fixed as so:

--- a/ReLaxExample/ReLaxTopShelfExample/ServiceProvider.swift
+++ b/ReLaxExample/ReLaxTopShelfExample/ServiceProvider.swift
@@ -8,7 +8,7 @@ class ServiceProvider: NSObject, TVTopShelfProvider {
     private let posterImages: [ParallaxImage] = titles
         .map { $0.lowercased().components(separatedBy: .whitespaces).joined() }
         .map { movie in
-            ["5", "4", "3", "2", "1"].map { return "\(movie)-\($0)" }
+            ["5"].map { return "\(movie)-\($0)" }
         }
         .compactMap {
             $0.compactMap { UIImage(named: $0) }

However, it seems that now disk based urls cannot be used for images in the top shelf. The image is never rendered on screen:

[tmm1]

Re-Lax/ReLaxExample/ReLaxTopShelfExample/ServiceProvider.swift

Line 25 in 38739c2

guard let cachesDirectory = try? FileManager.default.url(for: FileManager.SearchPathDirectory.cachesDirectory, in: FileManager.SearchPathDomainMask.userDomainMask, appropriateFor: nil, create: false) else { return nil }

This returns a URL like file:///var/mobile/Containers/Data/PluginKitPlugin/523B8F53-D249-461C-B789-15E186677923/Library/Caches/ which used to work for serving images to the top shelf, but seems no longer does.

[marksands]

Oof--thanks, @tmm1. I'll see if there's any workarounds, but I'll likely have to shout into the void file a radar about this. I spoke with one of the tvOS engineers a few years back and he assured me loading URLs from the cache to be displayed in top shelf is expected behavior, but sounds like that might've changed. 😞

[tmm1]

Yea, real bummer.

I just opened a radar too, for reference:

FB8122159 TVTopShelfSectionedItem with file:// based imageURL does not display

Before tvOS 13.4, a top shelf extension could generate/save images in the cache directory and then serve them into the top shelf using setImageURL: with the file:// based URL for the image on disk.

After 13.4 and in tvOS 14 Beta 1/2/3, the images are no longer displayed. See attached image.

[marksands]

If any Apple 👀 are watching, I filed two radars: FB8122798 and FB8122874.

[laurent-humbert]

You only have a nano second to provide the TVTopShelfSectionedContent. It's not possible to issue even the simplest http request, or generate a thumbnail using UIGraphicsImageRenderer etc. All that work has to be done by the app, (in a BGAppRefreshTask probably) and the resulting data (thumbnails etc...) saved in a group folder. Then it's fine to just use the file url.

[tmm1]

You only have a nano second to provide the TVTopShelfSectionedContent. It's not possible to issue even the simplest http request, or generate a thumbnail using UIGraphicsImageRenderer etc.

Not sure I follow. I'm making HTTP requests and it works just fine. The new TVService api in 13.0 uses a completion handler to make this even easier. Apple's own BuildingAFullScreenTopShelfExtension example uses dispatch queue to calculate the top shelf contents, and even mentions a network request in the code comments.

I also tried already to cache the generated files and even when they're ready on disk and returned right away, it never renders inside the Top Shelf.

saved in a group folder

Maybe this is the key.. what do you mean by group folder?

[tmm1]

Maybe this is the key.. what do you mean by group folder?

Okay I can confirm this works. See https://developer.apple.com/forums/thread/23418

file:///var/mobile/Containers/Data/PluginKitPlugin/523B8F53-D249-461C-B789-15E186677923/Library/Caches/

The new path with proper permissions to render inside Top Shelf looks like file:///private/var/mobile/Containers/Shared/AppGroup/2F333855-1798-4D86-9C92-E8E9D45C0119/Library/Caches/

[marksands]

Awesome--I'll be unavailable for most of the weekend but I'll experiment and correct the example code as soon as I can.

[laurent-humbert]

You only have a nano second to provide the TVTopShelfSectionedContent. It's not possible to issue even the simplest http request, or generate a thumbnail using UIGraphicsImageRenderer etc.

Not sure I follow. I'm making HTTP requests and it works just fine. The new TVService api in 13.0 uses a completion handler to make this even easier. Apple's own BuildingAFullScreenTopShelfExtension example uses dispatch queue to calculate the top shelf contents, and even mentions a network request in the code comments.

Like you at first I was happy to see the completion handler. But I couldn't get any http request to complete (It does work in the Simulator though). Maybe they have fixed it in more recent version of iOS 13.

I also tried already to cache the generated files and even when they're ready on disk and returned right away, it never renders inside the Top Shelf.

saved in a group folder

Maybe this is the key.. what do you mean by group folder?

The new path with proper permissions to render inside Top Shelf looks like

It's bizarre the extension wouldn't have read access to its own Cache folder.