DJI SDK获取最后一张图片

Question

I am currently trying to access the last image taken by a DJI Phantom 4 using the mobile SDK. I have looked at: How to programmatically download Images from drone using the IOS DJI-SDK and it has helped, however, while in the .refreshFileList() call, an error is thrown that says 'Execution of this process has timed out(code -1003)'.

Any help would be greatly appreciated! Here is my code:

/***** Setup Camera *****/

// get current product
guard let drone = DJISDKManager.product() else {
    print("Product is connected but DJISDKManager.product is nil when attempting to download media")
    return
}

// Get camera on drone
guard  let camera: DJICamera = drone.camera else {
    print("Unable to detect Camera in initDownload()")
    return
}

print("Successfully detected the camera")


// take picture when project starts
camera.startShootPhoto(completion: { (error) in

    if (error != nil) {
        print("Shoot photo error: \(error.debugDescription)")
    }

})


/***** Get Last Picture *****/

// check if we can download images with the product
if !camera.isMediaDownloadModeSupported() {
    print("Product does not support media download mode")
    return
}

print("before set mode...")

// switch camera mode to allow for media downloads
camera.setMode( .mediaDownload, withCompletion: {(error) in

    print("in set mode...")

    if error != nil {

        print(("\(error!.localizedDescription)"))

    } else {

        // get the media manager from the drone to gain access to the files
        let manager = camera.mediaManager!

        manager.refreshFileList(of: DJICameraStorageLocation.sdCard, withCompletion:  { (error) in

            print("in refresh file list...")

            if error != nil {

                ///////TIMES OUT HERE/////////

                print("Refresh error State: \(manager.sdCardFileListState.rawValue)")
                print("Error refreshing list: \(error!.localizedDescription)")

            }else {

                print("Refreshed file list")
                print("No error State: \(manager.sdCardFileListState.rawValue)")

                // get list of files
                guard let files = manager.sdCardFileListSnapshot() else {
                    print("No files to download")
                    return
                }

                print("There are files to download.. Beginning Download")
                print(("files \(files.count)"))
            }
        }) // end of file-refresh block
    } // end of if else
})// end of camera setMode block

Answer 1

The issue with your code is that you are not waiting for the completion of the startShootPhoto action to finish before changing modes. This might be what is causing your error.

Here is working version of your function

 func shootPhoto() {
    guard let drone = (DJISDKManager.product() as? DJIAircraft) else {
        print("Product is connected but DJISDKManager.product is nil when attempting to download media")
        return
    }

    // Get camera on drone
    guard  let camera: DJICamera = drone.camera else {
        print("Unable to detect Camera in initDownload()")
        return
    }

    print("Successfully detected the camera")


    // take picture when project starts
    camera.startShootPhoto(completion: { (error) in

        if (error != nil) {
            print("Shoot photo error: \(error.debugDescription)")
        }
        else {
            self.getLastImage(camera: camera)
        }

    })

}

func getLastImage(camera: DJICamera) {
    /***** Get Last Picture *****/

    // check if we can download images with the product
    if !camera.isMediaDownloadModeSupported() {
        print("Product does not support media download mode")
        return
    }

    print("before set mode...")
    let retry = RetryManager() // Run the same block multiple times if the command has an error
    // switch camera mode to allow for media downloads
    retry.runBlock(withRetries: 5) {
        camera.setMode( .mediaDownload, withCompletion: {(error) in

            print("in set mode...")

            if error != nil {

                print(("\(error!.localizedDescription)"))

            } else {
                retry.stop()
                // get the media manager from the drone to gain access to the files
                let manager = camera.mediaManager!

                manager.refreshFileList(of: DJICameraStorageLocation.sdCard, withCompletion:  { (error) in

                    print("in refresh file list...")

                    if error != nil {

                        ///////TIMES OUT HERE/////////

                        print("Refresh error State: \(manager.sdCardFileListState.rawValue)")
                        print("Error refreshing list: \(error!.localizedDescription)")

                    }else {

                        print("Refreshed file list")
                        print("No error State: \(manager.sdCardFileListState.rawValue)")

                        // get list of files
                        guard let files = manager.sdCardFileListSnapshot() else {
                            print("No files to download")
                            return
                        }

                        print("There are files to download.. Beginning Download")
                        print(("files \(files.count)"))
                    }
                }) // end of file-refresh block
            } // end of if else
            retry.proceed()
        })// end of camera setMode block
    }

}

This code works for me, here is the gist for the retry manager, I had to use it since the first couple attempts failed. https://gist.github.com/justinmiller62/4c76d9704524fd8aaa60e166a5cccea8

Additionally if you want your code inline instead of nested like this, you can use semaphores to wait until the previous function is complete.