Bug 277794 – WKWebview does not render AVIF images on macOS in "designed for iPad" iOS apps

• Status: RESOLVED
• Resolution: FIXED
• Component: Images

[Martin Knudsen]

Created attachment 472076 [details]
WKWebView in an app not rendering AVIF images

If I run any WKWebKit based iOS app on my silicon mac it fails to render AVIF images consistently.

This can be reproduced with test apps in the mac app store like https://apps.apple.com/de/app/webview-wkwebview-and-uiwebview-rendering/id928647773?l=en-GB

WKWebView does not render AVIF images. UIWebView does appear to render them.

Software versions:

macOS 14.6 (23G80)
Safari Version 17.6 (19618.3.11.11.5)

Steps to reproduce:
 
- load a WKWebView using app like https://apps.apple.com/de/app/webview-wkwebview-and-uiwebview-rendering/id928647773?l=en-GB on an Apple Silicon mac
- select WKWebView
- enter https://www.otto.de/apps-assets/images.html (or any other AVIF displaying website like https://test-images.github.io/avif/202105/squoosh/losssless7/ ) as the URL to load
- press go

result:
- AVIF images do not render correctly, JPEG image renders correctly

expected:
- AVIF images to be displayed the same as on UIWebView

Selecting UIWebView shows images as expected.

I cannot reproduce this with either mobile Safari on iOS or (stable, preview) Desktop Safari on my Mac itself so it seems specific to iOS apps being run on mac OS.

I also filed issues through the Apple feedback assistant, IDs FB14711263 and FB14678252 .

Let me know if I can add any more information.

[Martin Knudsen]

Created attachment 472077 [details]
UIWebView in app rendering AVIF images successfully

[Alexey Proskuryakov]

rdar://133272264

[Martin Knudsen]

The test app I mentioned seems removed from the app store, this one demonstrates the issue as well.

[Martin Knudsen]

This issue seems fixed with macOS 15.0 (24A335), will verify with 14.7 too.

[Martin Knudsen]

Still broken 14.7 (23H124) and Safari Version 18.0 (19619.1.26.111.10, 19619). Sequoia / 15 looks good though.

[Per Arne Vollan]

rdar://108458357