Creating a Media Manager Application

2018-11-20v4.8.1Github

If you come across any mistakes or bugs in this tutorial, please let us know using a Github issue, a post on the DJI forum. Please feel free to send us Github pull request and help us fix any issues.


In this tutorial, you will learn how to use the DJIMediaManager to interact with the file system on the SD card of the aircraft's camera. By the end of this tutorial, you will have an app that you can use to preview photos, play videos, download or delete files and so on.

In order for our app to manage photos and videos, however, it must first be able to take and record them. Fortunately, by using DJI iOS UX SDK, you can implement shooting photos and recording videos functionalities easily with standard DJI Go UIs.

You can download the tutorial's final sample project from this Github Page.

We use Mavic Pro and iPad Air as an example to make this demo. For more details of customizing the layouts for iPhone devices, please check the tutorial's Github Sample Project.

Application Activation and Aircraft Binding in China

For DJI SDK mobile application used in China, it's required to activate the application and bind the aircraft to the user's DJI account.

If an application is not activated, the aircraft not bound (if required), or a legacy version of the SDK (< 4.1) is being used, all camera live streams will be disabled, and flight will be limited to a zone of 100m diameter and 30m height to ensure the aircraft stays within line of sight.

To learn how to implement this feature, please check this tutorial Application Activation and Aircraft Binding.

Implementing DJI Go Style Default Layout

Importing DJI SDK and UX SDK with CocoaPods

To create a new project in Xcode, choose Single View Application template for your project and press "Next", then enter "MediaManagerDemo" in the Product Name field and keep the other default settings. Once the project is created, import the DJI SDK and DJI UX SDK.

You can check Getting Started with DJI UX SDK tutorial to learn how to import the DJISDK.framework and DJIUXSDK.framework into your Xcode project.

Importing the DJIWidget

You can check Creating a Camera Application tutorial to learn how to download and import the DJIWidget into your Xcode project.

Working on the MainViewController and DefaultlayoutViewController

You can check this tutorial's Github Sample Code to learn how to implement the MainViewController to do SDK registration and update UIs and show alert views to inform users when DJI product is connected and disconnected. Also, you can learn how to implement shooting photos and recording videos functionalities with standard DJI Go UIs by using DUXDefaultLayoutViewcontroller of DJI UX SDK from the Getting Started with DJI UX SDK tutorial.

If everything goes well, you can see the live video feed and test the shoot photo and record video features like this:

connectToAircraft

Congratulations! We can move forward now.

Working on the UI of the Application

Now, to create a new file, choose the "Cocoa Touch Class" template and choose UIViewController as its subclass, name it as "MediaManagerViewController". We will use it to implement the Media Manager features.

Next, open the Main.storyboard file and drag and drop a new "View Controller" object from the Object Library and set its "Class" value as MediaManagerViewController.

Moreover, drag and drop a new "Container View" object in the MediaManagerViewController and set its ViewController's "Class" value as DUXFPVViewController, which contains a DUXFPVView and will show the video playback.

Furthermore, drag and drop a UIImageView object on top of the "Container View" and hide it as default, we will use it to show the downloaded photo. Moreover, drag and drop eleven UIButton objects, one UITextField, one UITableView and a UIActivityIndicatorView, place them in the following positions:

mediaManagerVCUI

The layout of the UI elements is a bit complicated, for more details of the configuration, please check the Main.storyboard in this tutorial's Github Sample Project.

Lastly, drag and place a UIButton on the bottom right corner of the DefaultLayoutViewController view and create a segue to show the MediaManagerViewController when the user press the button.

If everything goes well, you should see the whole storyboard layout like this:

mediaManagerVCUI

Once you finish the above steps, open the "DefaultLayoutViewController.m" file and replace the content with the followings:

#import "DefaultLayoutViewController.h"
#import "DemoUtility.h"

@interface DefaultLayoutViewController ()
@property (weak, nonatomic) IBOutlet UIButton *mediaDownloadBtn;

@end

@implementation DefaultLayoutViewController

- (void)viewDidLoad
{
[super viewDidLoad];

if (IS_IPAD) {
[self.mediaDownloadBtn setImage:[UIImage imageNamed:@"mediaDownload_icon_iPad"] forState:UIControlStateNormal];
}else{
[self.mediaDownloadBtn setImage:[UIImage imageNamed:@"mediaDownload_icon"] forState:UIControlStateNormal];
}
}

@end

In the code above, we create an IBOutlet property for the mediaDownloadBtn and set its image in the viewDidLoad method. You can get the "mediaDownload_icon.png" and "mediaDownload_icon_iPad.png" files from this tutorial's Github Sample Project.

Next, open the "MediaManagerViewController.m" file and replace the content with the followings:

#import "MediaManagerViewController.h"
#import "DemoUtility.h"

@interface MediaManagerViewController ()
@property (weak, nonatomic) IBOutlet UITextField *positionTextField;
@property (weak, nonatomic) IBOutlet UITableView *mediaTableView;
@property (weak, nonatomic) IBOutlet UIView *videoPreviewView;
@property (weak, nonatomic) IBOutlet UIButton *editBtn;
@property (weak, nonatomic) IBOutlet UIButton *deleteBtn;
@property (weak, nonatomic) IBOutlet UIButton *cancelBtn;
@property (weak, nonatomic) IBOutlet UIButton *reloadBtn;
@property (weak, nonatomic) IBOutlet UIImageView *displayImageView;
@property (weak, nonatomic) IBOutlet UIActivityIndicatorView *loadingIndicator;

@end

@implementation MediaManagerViewController

- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
}

- (void)viewDidLoad {
[super viewDidLoad];
[self initData];

}

- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}

- (BOOL)prefersStatusBarHidden {
return NO;
}

#pragma mark - Custom Methods
- (void)initData
{
[self.deleteBtn setEnabled:NO];
[self.cancelBtn setEnabled:NO];
[self.reloadBtn setEnabled:NO];
[self.editBtn setEnabled:NO];
}

#pragma mark - IBAction Methods
- (IBAction)backBtnAction:(id)sender {
[self.navigationController popViewControllerAnimated:YES];
}

- (IBAction)editBtnAction:(id)sender {
[self.mediaTableView setEditing:YES animated:YES];
[self.deleteBtn setEnabled:YES];
[self.cancelBtn setEnabled:YES];
[self.editBtn setEnabled:NO];
}

- (IBAction)cancelBtnAction:(id)sender {
[self.mediaTableView setEditing:NO animated:YES];
[self.editBtn setEnabled:YES];
[self.deleteBtn setEnabled:NO];
[self.cancelBtn setEnabled:NO];
}

- (IBAction)reloadBtnAction:(id)sender {
}

- (IBAction)statusBtnAction:(id)sender {
}

- (IBAction)downloadBtnAction:(id)sender {
}

- (IBAction)playBtnAction:(id)sender {
}

- (IBAction)resumeBtnAction:(id)sender {
}

- (IBAction)pauseBtnAction:(id)sender {
}

- (IBAction)stopBtnAction:(id)sender {
}

- (IBAction)moveToPositionAction:(id)sender {
}

- (IBAction)showStatusBtnAction:(id)sender {
}

In the code above, we implement the following things:

  1. Firstly, we define the IBOutlet properties for the UI elements, like UIButton, UITableView, UITextField, etc.

  2. Next, we implement the viewDidLoad method, and invoke the initData method to disable the deleteBtn, cancelBtn, reloadBtn and editBtn initially.

  3. Lastly, we implement the IBAction methods for all the UIButtons. For the backBtnAction method, we invoke the popViewControllerAnimated method of UINavigationController to go back to the DefaultLayoutViewController.

For the editBtnAction method, we make mediaTableView goes into editing mode by invoking setEditing:animated: method of UITableView. Then enable the deleteBtn and cancelBtn buttons, disable the editBtn button.

For the cancelBtnAction method, on contract, we disable the editing mode of mediaTableView and enable the editBtn button, also disable the deleteBtn and cancelBtn buttons. We will implement the other IBAction methods later.

Switching to Media Download Mode

In order to preview, edit or download the photos or videos files from the DJICamera, you need to use the DJIPlaybackManager or DJIMediaManager of DJICamera. Here, we use DJIMediaManager to demonstrate how to implement it.

Now, create a property of DJIMediaManager in the class extension part and implement the viewWillAppear: and viewWillDisappear: methods as shown below:

@property (nonatomic, weak) DJIMediaManager *mediaManager;
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
DJICamera *camera = [DemoUtility fetchCamera];
if (camera != nil) {
camera.delegate = self;
self.mediaManager = camera.mediaManager;
self.mediaManager.delegate = self;
[camera setMode:DJICameraModeMediaDownload withCompletion:^(NSError *error) {
if (error) {
NSLog(@"setMode failed: %@", error.description);
}
}];
}
}

- (void)viewWillDisappear:(BOOL)animated
{
[super viewWillDisappear:animated];
DJICamera *camera = [DemoUtility fetchCamera];
[camera setMode:DJICameraModeShootPhoto withCompletion:^(NSError * _Nullable error) {
if (error) {
ShowResult(@"Set CameraWorkModeShootPhoto Failed, %@", error.description);
}
}];

if (camera && camera.delegate == self) {
[camera setDelegate:nil];
self.mediaManager.delegate = nil;
}
}

In the code above, we implement the following things:

  1. In the viewWillAppear method, we firstly invoke the fetchCamera method of DemoUtility class to fetch the DJICamera object. Then check if the camera is nil, if not set its delegate as MediaManagerViewController, also initialize the mediaManager and set its delegate as MediaManagerViewController. Furthermore, invoke the setMode:withCompletion: method of DJICamera and pass the DJICameraModeMediaDownload param to switch the camera mode to media download mode.

  2. Similarly, in the viewWillDisappear method, we also invoke the setMode:withCompletion: method of DJICamera and pass the DJICameraModeShootPhoto param to switch the camera mode to shoot photo mode. Then reset the delegates of DJICamera and DJIMediaManager. So when the user enter the MediaManagerViewController, the DJICamera will switch to media download mode automatically, when user exit back to the DefaultLayoutViewController, the DJICamera will switch to shoot photo mode.

Refreshing Media File List

Once we have finished the steps above, we can start to fetch the media files list from the Camera SD card and show them on the tableView.

Create the following properties in the class extension part and initialize it in the initData method:

@property(nonatomic, strong) NSMutableArray* mediaList;
@property (nonatomic, strong) NSIndexPath *selectedCellIndexPath;
- (void)initData
{
self.mediaList = [[NSMutableArray alloc] init];
...
}

Next, create two new methods: loadMediaList and updateMediaList: and invoke the loadMediaList method at the bottom of viewWillAppear: method and reloadBtnAction: IBAction method:

- (void)viewWillAppear:(BOOL)animated
{
...
if (camera != nil) {
...
[self loadMediaList];
}
}

- (IBAction)reloadBtnAction:(id)sender {
[self loadMediaList];
}

-(void) loadMediaList
{
[self.loadingIndicator setHidden:NO];
if (self.mediaManager.sdCardFileListState == DJIMediaFileListStateSyncing || self.mediaManager.sdCardFileListState == DJIMediaFileListStateDeleting) {
NSLog(@"Media Manager is busy. ");
}else {
WeakRef(target);
[self.mediaManager refreshFileListOfStorageLocation:DJICameraStorageLocationSDCard withCompletion:^(NSError * _Nullable error) {
WeakReturn(target);
if (error) {
ShowResult(@"Fetch Media File List Failed: %@", error.localizedDescription);
}
else {
NSLog(@"Fetch Media File List Success.");
NSArray *mediaFileList = [target.mediaManager sdCardFileListSnapshot];
[target updateMediaList:mediaFileList];
}
[target.loadingIndicator setHidden:YES];
}];
}
}

-(void) updateMediaList:(NSArray*)mediaList
{
[self.mediaList removeAllObjects];
[self.mediaList addObjectsFromArray:mediaList];

DJIFetchMediaTaskScheduler *taskScheduler = [DemoUtility fetchCamera].mediaManager.taskScheduler;
taskScheduler.suspendAfterSingleFetchTaskFailure = NO;
[taskScheduler resumeWithCompletion:nil];
for (DJIMediaFile *file in self.mediaList) {
if (file.thumbnail == nil) {
WeakRef(target);
DJIFetchMediaTask *task = [DJIFetchMediaTask taskWithFile:file content:DJIFetchMediaTaskContentThumbnail andCompletion:^(DJIMediaFile * _Nullable file, DJIFetchMediaTaskContent content, NSError * _Nullable error) {
WeakReturn(target);
[target.mediaTableView reloadData];
}];
[taskScheduler moveTaskToEnd:task];
}
}

[self.reloadBtn setEnabled:YES];
[self.editBtn setEnabled:YES];
}

The code above implements:

  1. In the loadMediaList method, we firstly show the loadingIndicator and check the fileListState enum value of the DJIMediaManager. If the value is DJIMediaFileListStateSyncing or DJIMediaFileListStateDeleting, we show an NSLog to inform users that the media manager is busy. For other values, we invoke the refreshFileListOfStorageLocation: method of the DJIMediaManager to refresh the file list from the SD card. In the completion block, if there is no error, we should get a copy of the current file list by invoking the fileListSnapshot method of DJIMediaManager and initialize the mediaFileList variable. Then invoke the updateMediaList: method and pass the mediaFileList. Lastly, hide the loadingIndicator since the operation of refreshing the file list has finished.

  2. In the updateMediaList: method, we firstly remove all the objects in the mediaList array and add new objects to it from the mediaList array. Next, create a mediaTaskScheduler variable and assign it with the taskScheduler property of DJIMediaManager. Then, assign NO to the suspendAfterSingleFetchTaskFailure property of DJIFetchMediaTaskScheduler to prevent from suspending the scheduler when an error occurs during the execution. Moreover, invoke the resumeWithCompletion method of DJIFetchMediaTaskScheduler to resume the scheduler, which will execute tasks in the queue sequentially.

Furthermore, create a for loop to loop through all the DJIMediaFile variables in the mediaList array and invoke the taskWithFile:content:andCompletion: method of DJIFetchMediaTaskScheduler by passing the file variable and DJIFetchMediaTaskContentThumbnail value to ask the scheduler to download the thumbnail of the media file.

In the completion block, we invoke the reloadData method of UITableView to reload everything in the table view. After that, invoke the moveTaskToEnd method to push the task to the back of the queue and be executed after the executing task is complete.

Lastly, we enable the reloadBtn and editBtn buttons.

Once you finish the steps above, you should implement the following UITableView methods:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

return self.mediaList.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"mediaFileCell"];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"mediaFileCell"];
}

if (self.selectedCellIndexPath == indexPath) {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}else
{
cell.accessoryType = UITableViewCellAccessoryNone;
}

DJIMediaFile *media = [self.mediaList objectAtIndex:indexPath.row];
cell.textLabel.text = media.fileName;
cell.detailTextLabel.text = [NSString stringWithFormat:@"Create Date: %@ Size: %0.1fMB Duration:%f cusotmInfo:%@", media.timeCreated, media.fileSizeInBytes / 1024.0 / 1024.0,media.durationInSeconds, media.customInformation];
if (media.thumbnail == nil) {
[cell.imageView setImage:[UIImage imageNamed:@"dji.png"]];
}
else
{
[cell.imageView setImage:media.thumbnail];
}

return cell;
}

In the code above, we implement the following features:

  1. Return 1 as the section number of the table view.
  2. Return the count value of the mediaList array as the number of rows in section.
  3. If the UITableViewCell selected, set its accessoryType as UITableViewCellAccessoryCheckmark to show a checkmark on the right side of the table view cell, otherwise, set the accessoryType as UITableViewCellAccessoryNone to hide the checkmark.

Next, get the DJIMediaFile object in the self.mediaList array by using the indexPath.row index. Lastly, update the textLabel, detailTextLabel and imageView properties of table view cell according to the DJIMediaFile object. For the "dji.png" file, you can get it from the tutorial's Github Sample project.

Now, to build and run the project, connect the demo application to a Mavic Pro (Please check the Run Application for more details) and enter the MediaManagerViewController, you should be able to see something similar to the following screenshot:

Downloading and Editing the Media Files

After showing all the media files in the table view, we can start to implement the features of downloading and deleting media files.

Now, continue to create the following properties in the class extension part:

@property(nonatomic, strong) DJIAlertView* statusAlertView;
@property(nonatomic) DJIMediaFile *selectedMedia;
@property(nonatomic) NSUInteger previousOffset;
@property(nonatomic) NSMutableData *fileData;

Next, initialize the properties in the initData method:

- (void)initData
{
...

self.fileData = nil;
self.selectedMedia = nil;
self.previousOffset = 0;
}

Moreover, implement the table View delegate method as shown below:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

if (self.mediaTableView.isEditing) {
return;
}

self.selectedCellIndexPath = indexPath;

DJIMediaFile *currentMedia = [self.mediaList objectAtIndex:indexPath.row];
if (![currentMedia isEqual:self.selectedMedia]) {
self.previousOffset = 0;
self.selectedMedia = currentMedia;
self.fileData = nil;
}

[tableView reloadData];
}

In the code above, we assign the selectedCellIndexPath property with the indexPath value. Then get the current selected currentMedia object from the mediaList array using the indexPath param of this method. Moreover, check if the currentMedia object is the same as self.selectedMedia property.

If not, reset the previousOffset and fileData properties and update the self.selectedMedia object with the currentMedia. Lastly, invoke the reloadData method to reload everything in the table view.

Once you finish the steps above, we continue to implement the downloadBtnAction: method as shown below:

- (IBAction)downloadBtnAction:(id)sender {

BOOL isPhoto = self.selectedMedia.mediaType == DJIMediaTypeJPEG || self.selectedMedia.mediaType == DJIMediaTypeTIFF;
WeakRef(target);
if (self.statusAlertView == nil) {
NSString* message = [NSString stringWithFormat:@"Fetch Media Data \n 0.0"];
self.statusAlertView = [DJIAlertView showAlertViewWithMessage:message titles:@[@"Cancel"] action:^(NSUInteger buttonIndex) {
WeakReturn(target);
if (buttonIndex == 0) {
[target.selectedMedia stopFetchingFileDataWithCompletion:^(NSError * _Nullable error) {
target.statusAlertView = nil;
}];
}
}];
}

[self.selectedMedia fetchFileDataWithOffset:self.previousOffset updateQueue:dispatch_get_main_queue() updateBlock:^(NSData * _Nullable data, BOOL isComplete, NSError * _Nullable error) {
WeakReturn(target);
if (error) {
[target.statusAlertView updateMessage:[[NSString alloc] initWithFormat:@"Download Media Failed:%@",error]];
[target performSelector:@selector(dismissStatusAlertView) withObject:nil afterDelay:2.0];
}
else
{
if (isPhoto) {
if (target.fileData == nil) {
target.fileData = [data mutableCopy];
}
else {
[target.fileData appendData:data];
}
}
target.previousOffset += data.length;
float progress = target.previousOffset * 100.0 / target.selectedMedia.fileSizeInBytes;
[target.statusAlertView updateMessage:[NSString stringWithFormat:@"Downloading: %0.1f%%", progress]];
if (target.previousOffset == target.selectedMedia.fileSizeInBytes && isComplete) {
[target dismissStatusAlertView];
if (isPhoto) {
[target showPhotoWithData:target.fileData];
[target savePhotoWithData:target.fileData];
}
}
}
}];
}

In the code above, we implement the following features:

  1. We firstly create a BOOL variable isPhoto and assign value to it by checking the mediaType enum value of the DJIMediaFile. For more details of the DJIMediaType enum, please check the "DJIMediaFile.h" file.

  2. Next, if the statusAlertView is nil, we initialize it by invoking the showAlertViewWithMessage:titles:action: method of DJIAlertView. Here we create a alertView with one button named "Cancel". If user press on the "Cancel" button of the alertView, we invoke the stopFetchingFileDataWithCompletion: method of DJIMediaFile to stop the fetch file task.

  3. Furthermore, invoke the fetchFileDataWithOffset:updateQueue:updateBlock: method of DJIMediaFile to fetch the media file's full resolution data from the SD card. The full resolution data could be either image or video. Inside the completion block, if there is an error, update message of the statusAlertView to inform users and dismiss the alert view after 2 seconds. If there is no error and the media file is a photo, initialize the fileData property or append data to it by checking if it is nil.

Next, accumulate the value of the previousOffset property by adding the length of the data param. Calculate the percentage of the current download progress and assign the value to the progress variable. Also, update the message of the statusAlertView to inform users of the download progress. Furthermore, check if the download has completed and dismiss the alert view.

Lastly, check if the media file is a photo, and invoke the showPhotoWithData: and savePhotoWithData: methods to show the full resolution photo and save it to the iOS Photo Library.

You can check the implementations of the showPhotoWithData: and savePhotoWithData: methods below:

-(void) showPhotoWithData:(NSData*)data
{
if (data) {
UIImage* image = [UIImage imageWithData:data];
if (image) {
[self.displayImageView setImage:image];
[self.displayImageView setHidden:NO];
}
}
}

#pragma mark Save Download Images
-(void) savePhotoWithData:(NSData*)data
{
if (data) {
UIImage* image = [UIImage imageWithData:data];
if (image) {
UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}
}
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{

NSString* message = @"";
if (error != NULL)
{
//Show message when save image failed
message = [NSString stringWithFormat:@"Save Image Failed! Error: %@", error];
}
else
{
//Show message when save image successfully
message = [NSString stringWithFormat:@"Saved to Photo Album"];
}

WeakRef(target);
if (self.statusAlertView == nil) {
self.statusAlertView = [DJIAlertView showAlertViewWithMessage:message titles:@[@"Dismiss"] action:^(NSUInteger buttonIndex) {
WeakReturn(target);
if (buttonIndex == 0) {
[target dismissStatusAlertView];
}
}];
}
}

In the code above, we implement the following features:

  1. In the showPhotoWithData: method, we check if the data is not nil and create a UIImage object from it. Then check if the created image is not nil and show it on the displayImageView object.

  2. Similarly, in the savePhotoWithData: method, we create a UIImage object from the data param and invoke the UIImageWriteToSavedPhotosAlbum() method to save the image to the photos album.

  3. In the selector method, we firstly create a NSString object and set its value by checking if there is an error. Next, show the statusAlertView to inform the users of the message and dismiss the alert view when the users press on the Dismiss button.

Once you have finished the steps above, we can continue to implement the feature of deleting media files. Here we should implement the delegate methods of UITableView as shown below:

-(BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
return YES;
}

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath{
DJIMediaFile* currentMedia = [self.mediaList objectAtIndex:indexPath.row];
[self.mediaManager deleteFiles:@[currentMedia] withCompletion:^(NSArray<DJIMediaFile *> * _Nonnull failedFiles, NSError * _Nullable error) {
if (error) {
ShowResult(@"Delete File Failed:%@",error);
for (DJIMediaFile * media in failedFiles) {
NSLog(@"%@ delete failed",media.fileName);
}
}else
{
ShowResult(@"Delete File Successfully");
[self.mediaList removeObjectAtIndex:indexPath.row];
[self.mediaTableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationLeft];
}

}];
}

The code above implements:

  1. In the tableView:canEditRowAtIndexPath: method, return YES to allow the swipe gesture to delete the table view cell.

  2. In the tableView:commitEditingStyle:forRowAtIndexPath: method, we get the currentMedia object from the mediaList array firstly. Next, invoke the deleteFiles:withCompletion: method of DJIMediaManager to delete the select media file. Inside the completion block, if there is an error, show an alert view to inform user of the error description. If not, remove the deleted media file from the mediaList array and invoke the deleteRowsAtIndexPaths:withRowAnimation: method of mediaTableView to remove the table view cell too.

Now, to build and run the project, connect the demo application to a Mavic Pro and enter the MediaManagerViewController, try to download an image file from the SD card, display and save it to the photos album. Also, try to swipe right on the table view cell and delete the media file from the table view. If everything goes well, you should be able to see something similar to the following gif animation:

Working on the Video Playback

After you finish the steps above, you should know how to download and display the image media file using DJIMediaManager, we can continue to implement the Video Playback features.

Now, implement the following IBAction methods:

- (IBAction)playBtnAction:(id)sender {

[self.displayImageView setHidden:YES];
if ((self.selectedMedia.mediaType == DJIMediaTypeMOV) || (self.selectedMedia.mediaType == DJIMediaTypeMP4)) {
[self.positionTextField setPlaceholder:[NSString stringWithFormat:@"%d sec", (int)self.selectedMedia.durationInSeconds]];
[self.mediaManager playVideo:self.selectedMedia withCompletion:^(NSError * _Nullable error) {
if (error) {
ShowResult(@"Play Video Failed: %@", error.description);
}
}];
}
}

- (IBAction)resumeBtnAction:(id)sender {

[self.mediaManager resumeWithCompletion:^(NSError * _Nullable error) {
if (error) {
ShowResult(@"Resume failed: %@", error.description);
}
}];
}

- (IBAction)pauseBtnAction:(id)sender {
[self.mediaManager pauseWithCompletion:^(NSError * _Nullable error) {
if (error) {
ShowResult(@"Pause failed: %@", error.description);
}
}];
}

- (IBAction)stopBtnAction:(id)sender {
[self.mediaManager stopWithCompletion:^(NSError * _Nullable error) {
if (error) {
ShowResult(@"Stop failed: %@", error.description);
}
}];
}

- (IBAction)moveToPositionAction:(id)sender {
NSUInteger second = 0;
if (self.positionTextField.text.length) {
second = [self.positionTextField.text floatValue];
}

WeakRef(target);
[self.mediaManager moveToPosition:second withCompletion:^(NSError * _Nullable error) {
WeakReturn(target);
if (error) {
ShowResult(@"Move to position failed: %@", error.description);
}
[target.positionTextField setText: @""];
}];

}

In the code above, we implement the following features:

  1. In the playBtnAction: method, we firstly hide the displayImageView image view. Then check the mediaType enum value of the selectedMedia object to see if the selected media file is a video. Furthermore, update the placeholder string of the positionTextField with the video duration and invoke the playVideo:withCompletion: method of DJIMediaManager to start playing the video.

  2. In the resumeBtnAction: method, we invoke the resumeWithCompletion: method of DJIMediaManager to resume the paused video.

  3. In the pauseBtnAction: method, we invoke the pauseWithCompletion: method of DJIMediaManager to pause the playing video.

  4. In the stopBtnAction: method, we call the stopWithCompletion: method of DJIMediaManager to stop the playing video.

  5. In the moveToPositionAction: method, we get the text value of the positionTextField and convert it to an NSUInteger value second. Then invoke the moveToPosition:withCompletion: method of DJIMediaManager to skip to the input position in seconds from the start of the video. Inside the completion block, we clean up the text content of the positionTextField.

Lastly, we can show the video playback state info by implementing the following methods:

- (void)initData
{
...

self.statusView = [DJIScrollView viewWithViewController:self];
[self.statusView setHidden:YES];
}

- (IBAction)showStatusBtnAction:(id)sender {
[self.statusView setHidden:NO];
[self.statusView show];
}

#pragma mark - DJIMediaManagerDelegate Method

- (void)manager:(DJIMediaManager *)manager didUpdateVideoPlaybackState:(DJIMediaVideoPlaybackState *)state {
NSMutableString *stateStr = [NSMutableString string];
if (state.playingMedia == nil) {
[stateStr appendString:@"No media\n"];
}
else {
[stateStr appendFormat:@"media: %@\n", state.playingMedia.fileName];
[stateStr appendFormat:@"Total: %f\n", state.playingMedia.durationInSeconds];
[stateStr appendFormat:@"Orientation: %@\n", [self orientationToString:state.playingMedia.videoOrientation]];
}
[stateStr appendFormat:@"Status: %@\n", [self statusToString:state.playbackStatus]];
[stateStr appendFormat:@"Position: %f\n", state.playingPosition];

[self.statusView writeStatus:stateStr];
}

-(NSString *)statusToString:(DJIMediaVideoPlaybackStatus)status {
switch (status) {
case DJIMediaVideoPlaybackStatusPaused:
return @"Paused";
case DJIMediaVideoPlaybackStatusPlaying:
return @"Playing";
case DJIMediaVideoPlaybackStatusStopped:
return @"Stopped";
default:
break;
}
return nil;
}

-(NSString *)orientationToString:(DJICameraOrientation)orientation {
switch (orientation) {
case DJICameraOrientationLandscape:
return @"Landscape";
case DJICameraOrientationPortrait:
return @"Portrait";
default:
break;
}
return nil;
}

In the code above, we implement the following features:

  1. At the bottom of the initData method, we initialize statusView and hide it. For more details of the DJIScrollView, please check the "DJIScrollView.h" and "DJIScrollView.m" files in the tutorial's Github Sample project.
  2. In the showStatusBtnAction: method, show the statusView when the users press the Status button.
  3. Implement the delegate method of DJIMediaManagerDelegate. We create a stateStr NSMutableString variable and append different string values to it. Like fileName, durationInSeconds and videoOrientation of the DJIMediaFile, for more details, please check the "DJIMediaFile" class. Lastly, invoke the writeStatus method of DJIScrollView to show the stateStr NSMutableString in the statusTextView of DJIScrollView.
  4. In the statusToString: and orientationToString: methods, return specific NSString values according to the values of the DJIMediaVideoPlaybackStatus and DJICameraOrientation enums.

Congratulations! You have finished all the features of this demo. Now build and run the project, connect the demo application to a Mavic Pro and enter the MediaManagerViewController, try to play with the Video Playback features. If everything goes well, you should be able to see something similar to the following gif animation:

Summary

In this tutorial, you have learned how to use DJIMediaManager to preview photos, play videos, download or delete files, you also learn how to get and show the video playback status info. By using the DJIMediaManager, the users can get the metadata for all the multimedia files, and has access to each individual multimedia file. Hope you enjoy it!