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I am developing an app using a data cable to link a camera. When I enter the page for the first time, I can detect the camera device, and then when I exit the page and enter again, I cannot detect the linked camera. - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view. self.view.backgroundColor = [UIColor whiteColor]; [self addImageCaptureCore]; } - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ [self checkCameraConnection]; }); } - (void)checkCameraConnection { if (@available(iOS 13.0, *)) { NSArray<ICDevice *> *connectedDevices = self.browser.devices; if (connectedDevices.count > 0) { NSLog(@"Camera is connected"); } else { NSLog(@"Camera is not connected"); } } else { // Fallback on earlier versions } } - (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; if (@available(iOS 13.0, *)) { if (self.cameraDevice) { if (self.cameraDevice.hasOpenSession) { [self.cameraDevice requestCloseSession]; dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ [self.browser stop]; self.browser.delegate = nil; self.browser = nil; }); } else { dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ [self.browser stop]; self.browser.delegate = nil; self.browser = nil; }); } } } else { // Fallback on earlier versions } } - (void)addImageCaptureCore { if (@available(iOS 13.0, *)) { ICDeviceBrowser *browser = [[ICDeviceBrowser alloc] init]; browser.delegate = self; [browser start]; self.browser = browser; } else { } } #pragma mark - ICDeviceBrowserDelegate - (void)deviceBrowser:(ICDeviceBrowser*)browser didAddDevice:(ICDevice*)device moreComing:(BOOL) moreComing API_AVAILABLE(ios(13.0)){ NSLog(@"Device name = %@",device.name); if ([device isKindOfClass:[ICCameraDevice class]]) { if ([device.capabilities containsObject:ICCameraDeviceCanAcceptPTPCommands]) { ICCameraDevice *cameraDevice = (ICCameraDevice *)device; cameraDevice.delegate = self; [cameraDevice requestOpenSession]; self.cameraDevice = cameraDevice; } } } - (void)deviceBrowser:(ICDeviceBrowser*)browser didRemoveDevice:(ICDevice*)device moreGoing:(BOOL) moreGoing API_AVAILABLE(ios(13.0)){ if (self.cameraDevice) { if (self.cameraDevice.hasOpenSession) { [self.cameraDevice requestCloseSession]; self.cameraDevice.delegate = nil; self.cameraDevice = nil; } else { self.cameraDevice.delegate = nil; self.cameraDevice = nil; } } } #pragma mark - ICCameraDeviceDelegate - (void)cameraDevice:(ICCameraDevice*)camera didAddItems:(NSArray<ICCameraItem*>*) items API_AVAILABLE(ios(13.0)){ if (items.count > 0) { ICCameraItem *latestItem = items.lastObject; NSLog(@"name = %@",latestItem.name); } } #pragma mark - ICDeviceDelegate - (void)device:(ICDevice*)device didOpenSessionWithError:(NSError* _Nullable) error API_AVAILABLE(ios(13.0)){ if (error) { NSLog(@"Failed to open session %@",error.localizedDescription); } else { NSLog(@"open session success"); } } - (void)device:(ICDevice*)device didCloseSessionWithError:(NSError* _Nullable)error API_AVAILABLE(ios(13.0)){ if (error) { NSLog(@"close session error = %@",error.localizedDescription); } else { NSLog(@"didCloseSession"); } } - (void)didRemoveDevice:(ICDevice*)device { }

I use a data cable to connect my Nikon camera to my iPhone. In my project, I use the framework ImageCaptureCore. Now I can read the photos in the camera memory card, but when I press the shutter of the camera to take a picture, the camera does not respond, the connection between the camera and the phone is normal. Then the camera screen shows a picture of a laptop. I don't know. Why is that? I hope someone can help me.