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April 15, 2020 00:01
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iPadOS 13.4: ImageCaptureCore's ICCameraFile `requestReadData(atOffset:length:completion:)` always passes empty Data object to completion block
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| import UIKit | |
| import ImageCaptureCore | |
| import MobileCoreServices | |
| class ViewController: UIViewController { | |
| var deviceFinder = DeviceFinder() | |
| override func viewDidLoad() { | |
| super.viewDidLoad() | |
| } | |
| } | |
| // MARK: - DeviceFinder | |
| class DeviceFinder: NSObject, ICDeviceBrowserDelegate { | |
| private var deviceBrowser: ICDeviceBrowser | |
| var devices: [ICCameraDevice: CameraDevice] = [:] | |
| override init() { | |
| self.deviceBrowser = ICDeviceBrowser() | |
| super.init() | |
| deviceBrowser.delegate = self | |
| deviceBrowser.start() | |
| print("[DeviceFinder] started ICDeviceBrowser; connect camera device now") | |
| } | |
| deinit { | |
| deviceBrowser.stop() | |
| } | |
| // MARK: ICDeviceBrowserDelegate | |
| func deviceBrowser(_ browser: ICDeviceBrowser, didAdd device: ICDevice, moreComing: Bool) { | |
| guard let device = device as? ICCameraDevice else { | |
| return | |
| } | |
| devices[device] = CameraDevice(device) | |
| } | |
| func deviceBrowser(_ browser: ICDeviceBrowser, didRemove device: ICDevice, moreGoing: Bool) { | |
| guard let device = device as? ICCameraDevice else { | |
| return | |
| } | |
| devices.removeValue(forKey: device) | |
| } | |
| } | |
| // MARK: - CameraDevice | |
| class CameraDevice: NSObject, ICCameraDeviceDelegate { | |
| let device: ICCameraDevice | |
| init(_ device: ICCameraDevice) { | |
| self.device = device | |
| super.init() | |
| self.device.delegate = self | |
| self.device.requestOpenSession() | |
| } | |
| // MARK: ICDeviceDelegate | |
| func device(_ device: ICDevice, didOpenSessionWithError error: Error?) { | |
| if let error = error { | |
| print("[CameraDevice] error opening session:", error) | |
| } else { | |
| print("[CameraDevice] session opened") | |
| } | |
| } | |
| func device(_ device: ICDevice, didCloseSessionWithError error: Error?) { | |
| } | |
| func didRemove(_ device: ICDevice) { | |
| } | |
| // MARK: ICCameraDeviceDelegate | |
| func deviceDidBecomeReady(withCompleteContentCatalog device: ICCameraDevice) { | |
| print("[CameraDevice] device ready, with complete catalog of \(device.mediaFiles?.count ?? 0) items") | |
| let cameraFiles = device.mediaFiles? | |
| .filter { ($0.uti ?? "") == (kUTTypeImage as String) } | |
| .compactMap { $0 as? ICCameraFile } ?? [] | |
| guard let file = cameraFiles.first else { | |
| print("[CameraDevice] there aren't any image files") | |
| return | |
| } | |
| print("[CameraDevice] about to requestReadData for file '\(file)' with size \(file.fileSize)") | |
| file.requestReadData(atOffset: 0, length: file.fileSize) { maybeData, maybeError in | |
| print("[CameraFile] in requestReadData completion block") | |
| if let error = maybeError { | |
| print("*** [CameraFile] error in requestReadData: \(error.localizedDescription)") | |
| } | |
| if let data = maybeData { | |
| if data.isEmpty { | |
| print("*** [CameraFile] data read via requestReadData is empty!") | |
| } else { | |
| print("*** [CameraFile] data read via requestReadData has \(data.count) bytes!") | |
| } | |
| } else { | |
| print("*** [CameraFile] data read via requestReadData is nil!") | |
| } | |
| } | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didAdd items: [ICCameraItem]) { | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didRemove items: [ICCameraItem]) { | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didCompleteDeleteFilesWithError error: Error?) { | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didReceiveMetadata metadata: [AnyHashable : Any]?, for item: ICCameraItem, error: Error?) { | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didReceiveThumbnail thumbnail: CGImage?, for item: ICCameraItem, error: Error?) { | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didRenameItems items: [ICCameraItem]) { | |
| } | |
| func cameraDeviceDidChangeCapability(_ camera: ICCameraDevice) { | |
| } | |
| func cameraDevice(_ camera: ICCameraDevice, didReceivePTPEvent eventData: Data) { | |
| } | |
| func cameraDeviceDidEnableAccessRestriction(_ device: ICDevice) { | |
| } | |
| func cameraDeviceDidRemoveAccessRestriction(_ device: ICDevice) { | |
| } | |
| } |
Filed as FB7663947 (http://www.openradar.me/FB7663947).
Mac Catalyst issue filed as FB7663990 (http://www.openradar.me/FB7663990).
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ImageCaptureCore: ICCameraFile requestReadData(atOffset:length:completion:) always passes empty Data object to completion block
Important: this is a regression in iPadOS 13.4. This has worked with previous versions of iPadOS, since beta versions of 13.2.
On iPadOS, ICCameraFile's
requestReadData(atOffset:length:completion:)method does not read data from the camera file.When
requestReadDatais called with an offset of 0 and a length corresponding to the size of the file, the completion block is executed with a non-nil, 0 byte Data object. (The error is nil.) The expected result is a Data object with the actual contents of the camera file (and a nil error), not a 0 byte Data object.The attached project reproduces this sample issue. (There is no app UI; see the messages logged to the console.) This project:
deviceDidBecomeReady(withCompleteContentCatalog:)delegate method is called,requestReadData(atOffset:length:completion:)is called with on the first ICCameraFile object. (Using the first ICCameraFile is arbitrary; the results are the same regardless of which file is chosen.)requestReadData(atOffset:length:completion:)completion block is subsequently called with a Data object that is 0 bytes in length.Example console output:
Instead, the expected output is:
For Open Radar: The minimum code sample to reproduce this is at https://gist.github.com/mjrusso/b223bf8db93e64d858e80b6fb8ab6ef8