Forgot to mention, I also tested passing an image created using UIImage(named:) to UIImageJPEGRepresentation, and it worked just fine on my real device.
I opened rdar://32829011 <rdar://32829011>, there is a test case in it, if you're interested. > On 18 Jun 2017, at 5:45 PM, Glen Huang <hey...@gmail.com> wrote: > > Thanks for the reply. > > I'm sorry but I'm not familiar with the "usual debugging things" that can be > apply to UIImage. Is there any official document introducing the inner > workings of UIImage that I can read? > > But following your advice, I did go check image.cgImage before passing it to > UIImageJPEGRepresentation, and it was not nil. Not sure what that implies. > > Also it seems a common problem according to > https://stackoverflow.com/questions/17440741/uiimagepngrepresentation-returns-nil-data > > <https://stackoverflow.com/questions/17440741/uiimagepngrepresentation-returns-nil-data> > > I tried the solution involving UIGraphicsBeginImageContext, and it works. > > I also tried simulator running iOS 10 (without using the solution), and it > works too. It only fails when running on a real device. > > What more can I do to find the real cause? > >> On 18 Jun 2017, at 1:29 PM, David Duncan <david.dun...@apple.com >> <mailto:david.dun...@apple.com>> wrote: >> >> >>> On Jun 16, 2017, at 7:31 AM, Glen Huang <hey...@gmail.com >>> <mailto:hey...@gmail.com>> wrote: >>> >>> Hi, >>> >>> I'm trying to extract the JPEG data from a PHAsset. I did it like this: >>> >>> let fetchOptions = PHFetchOptions() >>> fetchOptions.sortDescriptors = [NSSortDescriptor(key: >>> "creationDate", ascending: true)] >>> let assets = PHAsset.fetchAssets(with: fetchOptions) >>> jpg(for: assets[0]) >>> >>> where jpg(for:) is >>> >>> func jpg(for asset: PHAsset) { >>> let size = CGSize(width: 100, height: 100) >>> PHImageManager.default().requestImage(for: asset, targetSize: size, >>> contentMode: .aspectFit, options: nil) { image, info in >>> if let image = image { >>> let jpg = UIImageJPEGRepresentation(image, 0.8)! >>> } >>> } >>> } >>> >>> It works in the simulator running iOS 11, but fails on iPhone 5S every time >>> with >>> >>> fatal error: unexpectedly found nil while unwrapping an Optional value >>> >>> And the thing caused that error was the bang after the >>> UIImageJPEGRepresentation function. >>> >>> I'm using Xcode 9 beta, Swift 4, new build system, and the phone runs iOS >>> 10.3.2 >>> >>> Any idea why that happens and how I can extract the JPEG data from PHAsset? >> >> There is no obvious reason why this should fail, but the usual debugging >> things apply – what are the quality of image? (image.CGImage can still be >> nil, even if image is not). Does UIImageJPEGRepresentation() fail in any >> other situations? Can you reproduce this without using PHAsset? >> >>> >>> Thank you. >>> _______________________________________________ >>> >>> Cocoa-dev mailing list (Cocoa-dev@lists.apple.com >>> <mailto:Cocoa-dev@lists.apple.com>) >>> >>> Please do not post admin requests or moderator comments to the list. >>> Contact the moderators at cocoa-dev-admins(at)lists.apple.com >>> <http://lists.apple.com/> >>> >>> Help/Unsubscribe/Update your Subscription: >>> https://lists.apple.com/mailman/options/cocoa-dev/david.duncan%40apple.com >>> <https://lists.apple.com/mailman/options/cocoa-dev/david.duncan%40apple.com> >>> >>> This email sent to david.dun...@apple.com >> >> -- >> David Duncan >> > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
