iOS 13 - WkWebView BUG: audio stops when in background

Number:rdar://5022510114406400 Date Originated:
Status: Resolved:
Product:ios Product Version:ios 13
Classification:Bug Reproducible:yes
I've an app that uses WkWebView to play audio from Soundcloud and Mixcloud by using their javascript widget, on iOS 13.1 (13.0) the audio stops when the app is not in foreground, even when Audio is on in Background Modes.

When starting the playback this assertions is thrown:

Error acquiring assertion: <NSError: 0x282cf67c0; domain: RBSAssertionErrorDomain; code: 2; reason: "Required client entitlement is missing"> {  
userInfo = {  
  RBSAssertionAttribute = <RBSLegacyAttribute: 0x1592432e0; requestedReason: MediaPlayback; reason: MediaPlayback; flags: PreventTaskSuspend | PreventTaskThrottleDown | WantsForegroundResourcePriority>;  

And after entering background state the following assertion is thrown and audio suspended:


Can't end BackgroundTask: no background task exists with identifier 13 (0xd), or it may have already been ended. Break in UIApplicationEndBackgroundTaskError() to debug.   
[ProcessSuspension] Background task expired while holding WebKit ProcessAssertion (isMainThread? 1).  

This is not happening in iOS 12, where the audio plays normally when in background.


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