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On iOS 11, trying to retrieve the kAudioUnitProperty_AudioChannelLayout property returns different information than iOS 12:On iOS 11, AudioChannelLayout.mChannelLayoutTag returns kAudioChannelLayoutTag_UseChannelDescriptionsOn iOS 12, AudioChannelLayout.mChannelLayoutTag returns 6619138This is on an iPhone 7 plus and iOS 12 beta 4.Is this expected? If so, it seems to conflict with some open source projects like GStreamer that only supports kAudioChannelLayoutTag_UseChannelDescriptions.

I'm currently using NSProcessInfo.performExpiringActivityWithReason to execute a long running network request in the background. What happens to the NSURLSessionDownloadTask when the expiring activity expires before the request finishes? When the user comes back to the foreground we are seeing some request errors ("The request timed out" and "The network connection was lost."). How should we handle this situation? When the expiringActivity expires should we just assume the request will fail and we should start over? Are there any alternatives so we can get the response when the user comes back to the app?

Is it possible to defer region change events until the user has internet connection? The use case is we need to report the crossing to our server. However, if the user doesn't have internet, the request doesn't go through and we lose the background processing time to report the change when the user gets internet.This is somewhat common, especially if the user is using underground transportation like the subway.

Hi all,I'm working on a watchOS 4 application where I'd like to start a download task from a button that the user clicks. This may take a little while so we are using a background session in case the user lowers their wrist. This all works great if the app is Frontmost and the watch is connected to the phone. However, if the watch is standalone, the download task will never start even if the app is in the foreground.Is this the expected behavior? Looking at the example in https://developer.apple.com/videos/play/wwdc2017/216/, they make it sound like the download should always immediately start if the app is Frontmost and in the foreground.

Hi all,I'm working on a watchOS 4 application where I'd like to start a download task from a button that the user clicks. This may take a little while so we are using a background session in case the user lowers their wrist. This all works great if the app is Frontmost and the watch is connected to the phone. However, if the watch is standalone, the download task will never start even if the app is in the foreground.Is this the expected behavior? Looking at the example in https://developer.apple.com/videos/play/wwdc2017/216/, they make it sound like the download should always immediately start if the app is Frontmost and in the foreground.

I am successfully using self-sizing UICollectionViewCells in iOS 10 and iOS 11. However, in iOS 9 I am receiving the following crash:2017-11-20 10:57:15.527 [86301:3735747] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 0 beyond bounds for empty array'*** First throw call stack:( 0 CoreFoundation 0x00000001140a8f65 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x0000000112fb0deb objc_exception_throw + 48 2 CoreFoundation 0x0000000113f8ca94 -[__NSArrayM objectAtIndex:] + 212 3 UIKit 0x0000000116b09488 -[_UIFlowLayoutSection computeLayoutInRect:forSection:invalidating:] + 4625 4 UIKit 0x0000000116ab5b20 __56-[UICollectionViewFlowLayout _updateItemsLayoutForRect:]_block_invoke + 509 5 CoreFoundation 0x0000000113fd7ad2 __53-[__NSArrayM enumerateObjectsWithOptions:usingBlock:]_block_invoke + 114 6 CoreFoundation 0x0000000113fd71c2 -[__NSArrayM enumerateObjectsWithOptions:usingBlock:] + 194 7 UIKit 0x0000000116ab5851 -[UICollectionViewFlowLayout _updateItemsLayoutForRect:] + 575 8 UIKit 0x0000000116ab5f2e -[UICollectionViewFlowLayout _fetchItemsInfoForRect:] + 761 9 UIKit 0x0000000116ab1e1f -[UICollectionViewFlowLayout _layoutAttributesForItemsInRect:] + 515 10 UIKit 0x0000000116ab3582 -[UICollectionViewFlowLayout layoutAttributesForElementsInRect:] + 127 11 ..... 0x000000010f499e9a -[BaseCustomFlowLayout layoutAttributesForElementsInRect:] + 106 12 .... 0x000000010fa84212 _T05....24BaseSelfSizingFlowLayoutC27layoutAttributesForElementsSaySo016UICollectionViewfH0CGSgSC6CGRectV2in_tF + 242 13 .... 0x000000010fa8466f _T05....24BaseSelfSizingFlowLayoutC27layoutAttributesForElementsSaySo016UICollectionViewfH0CGSgSC6CGRectV2in_tFTo + 95 14 UIKit 0x0000000116ad17f4 __45-[UICollectionViewData validateLayoutInRect:]_block_invoke + 144 15 UIKit 0x0000000116ad1240 -[UICollectionViewData validateLayoutInRect:] + 3067 16 UIKit 0x0000000116a8183e -[UICollectionView layoutSubviews] + 196 17 UIKit 0x000000011632211c -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 710 18 QuartzCore 0x000000011542436a -[CALayer layoutSublayers] + 146 19 QuartzCore 0x0000000115418bd0 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 366 20 QuartzCore 0x0000000115418a4e _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24 21 QuartzCore 0x000000011540d1d5 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 277 22 QuartzCore 0x000000011543a9f0 _ZN2CA11Transaction6commitEv + 508 23 QuartzCore 0x000000011543b154 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92 24 CoreFoundation 0x0000000113fd49d7 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 25 CoreFoundation 0x0000000113fd4947 __CFRunLoopDoObservers + 391 26 CoreFoundation 0x0000000113fca59b __CFRunLoopRun + 1147 27 CoreFoundation 0x0000000113fc9e98 CFRunLoopRunSpecific + 488 28 GraphicsServices 0x0000000119ff6ad2 GSEventRunModal + 161 29 UIKit 0x0000000116271676 UIApplicationMain + 171 30 .... 0x000000010f0bbfbf main + 95 31 libdyld.dylib 0x00000001161ae92d start + 1)libc++abi.dylib: terminating with uncaught exception of type NSExceptionAny ideas?