Image/IO created image can not get correct frame count on macOS, however same image data works on iOS

Hi, is there the place to ask issue about Image/IO framework on macOS, because I can't find a space for Image/IO 🙂


I'm a iOS developer and recentlly trying to do some macOS related stuff about image. However, when using Image/IO to process some APNG format image(https://en.wikipedia.org/wiki/APNG), I face the issue that the Image/IO behavior different from iOS to macOS.


When using Image/IO's source API `CGImageSourceGetCount` on an APNG(Animated PNG) image data, The behavior is strange for some valid APNG image. On iOS(Tested iOS 8 - 11.0 with Simulator), the `CGImageSourceGetCount` return the correct frame count. However, on macOS(With the same `NSData`, which means same MD5), the `CGImageSourceGetCount` return 1. However, other image viewer like Chrome for Mac can show the correct rendering of APNG.


What I mean about "some valid APNG image" can be easily create by using Image/IO's destination API to encode a GIF image to APNG data. It can be show on Safari on iOS, Chrome for Mac, but fail on Safari for macOS.


I create a demo project on GitHub: https://github.com/dreampiggy/ImageIOAPNGTest . I wonder if someone can point out whether this is a usage problem or actual bug on Image/IO.


I also create a bug repoert #37650691, however, I was told by friends that the public bug reporter about framework issue seems will never to be check(Months or years later). So I guess if I can put the issue into the developer forum, I can get more information and may find the people who face the same issue. Thanks again.