Code to share file path/file between a share extension and iOS app

Question

I have added a share extension for my app say SAMPLE (already exists on the app store), called lets say SAMPLESHARE. Whenever a user, say takes a picture and tries to share

Answer 1

1. If you don't want show dialog default from apple. Should be inherit from UIViewController not @interface ShareViewController : SLComposeServiceViewController
2. In Apple developer document, don't permit Extensions app open directly Containing app except Today extension app.

Answer 2

Your question is a bit messed up but if it is about passing data from one app to another app you have a great solution for that which is UIPasteboard

If you don't have any problem for jumping between apps using custom URL handlers then you have 2 more steps left.

Step 1
In your first application which is responsible for passing data implement these methods and then call custom URL.

UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
[[UIPasteboard generalPasteboard] setImage:passImage];

Step 2
In your target view controller simple call UIPasteboard again and get the data from it.

UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
   UIImage *getImage = pasteboard.image;

Please note, that you pass a UIImage and you get it in the same type

Answer 3

UPDATE

The app was accepted in the review using NSUSERDEFAULTS as the message passing mechanism. Here are the steps.

1.) Share extension:

#import "ShareViewController.h"
#import <MobileCoreServices/UTCoreTypes.h>
//Macro to hide post dialog or not, if defined, will be hidden, comment during debugging
#define HIDE_POST_DIALOG

@interface ShareViewController ()

@end

@implementation ShareViewController

NSUInteger m_inputItemCount = 0; // Keeps track of the number of attachments we have opened asynchronously.
NSString * m_invokeArgs = NULL;  // A string to be passed to your AIR app with information about the attachments.
NSString * APP_SHARE_GROUP = @"group.com.schemename.nameofyourshareappgroup";
const NSString * APP_SHARE_URL_SCHEME = @"schemename";
CGFloat m_oldAlpha = 1.0; // Keeps the original transparency of the Post dialog for when we want to hide it.

- (BOOL)isContentValid {
    // Do validation of contentText and/or NSExtensionContext attachments here
    return YES;
}

- ( void ) didSelectPost
{
#ifdef HIDE_POST_DIALOG
    return;
#endif

    [ self passSelectedItemsToApp ];
    // Note: This call is expected to be made here. Ignore it. We'll tell the host we are done after we've invoked the app.
    //    [ self.extensionContext completeRequestReturningItems: @[] completionHandler: nil ];
}
- ( void ) addImagePathToArgumentList: ( NSString * ) imagePath
{
    assert( NULL != imagePath );

    // The list of arguments we will pass to the AIR app when we invoke it.
    // It will be a comma-separated list of file paths: /path/to/image1.jpg,/path/to/image2.jpg
    if ( NULL == m_invokeArgs )
    {
        m_invokeArgs = imagePath;
    }
    else
    {
        m_invokeArgs = [ NSString stringWithFormat: @"%@,%@", m_invokeArgs, imagePath ];
    }
}

- ( NSString * ) saveImageToAppGroupFolder: ( UIImage * ) image
                                imageIndex: ( int ) imageIndex
{
    assert( NULL != image );

    NSData * jpegData = UIImageJPEGRepresentation( image, 1.0 );

    NSURL * containerURL = [ [ NSFileManager defaultManager] containerURLForSecurityApplicationGroupIdentifier: APP_SHARE_GROUP ];
    NSString * documentsPath = containerURL.path;

    // Note that we aren't using massively unique names for the files in this example:
    NSString * fileName = [ NSString stringWithFormat: @"image%d.jpg", imageIndex ];

    NSString * filePath = [ documentsPath stringByAppendingPathComponent: fileName ];
    [ jpegData writeToFile: filePath atomically: YES ];

    //Mahantesh -- Store image url to NSUserDefaults

    NSUserDefaults *defaults=[[NSUserDefaults alloc] initWithSuiteName:@"group.com.schemename.nameofyourshareappgroup"];
    [defaults setObject:filePath forKey:@"url"];
    [defaults synchronize];

    return filePath;
}

- ( void ) passSelectedItemsToApp
{
    NSExtensionItem * item = self.extensionContext.inputItems.firstObject;

    // Reset the counter and the argument list for invoking the app:
    m_invokeArgs = NULL;
    m_inputItemCount = item.attachments.count;

    // Iterate through the attached files
    for ( NSItemProvider * itemProvider in item.attachments )
    {
        // Check if we are sharing a Image
        if ( [ itemProvider hasItemConformingToTypeIdentifier: ( NSString * ) kUTTypeImage ] )
        {
            // Load it, so we can get the path to it
            [ itemProvider loadItemForTypeIdentifier: ( NSString * ) kUTTypeImage
                                             options: NULL
                                   completionHandler: ^ ( UIImage * image, NSError * error )
             {
                 static int itemIdx = 0;

                 if ( NULL != error )
                 {
                     NSLog( @"There was an error retrieving the attachments: %@", error );
                     return;
                 }

                 // The app won't be able to access the images by path directly in the Camera Roll folder,
                 // so we temporary copy them to a folder which both the extension and the app can access:
                 NSString * filePath = [ self saveImageToAppGroupFolder: image imageIndex: itemIdx ];

                 // Now add the path to the list of arguments we'll pass to the app:
                 [ self addImagePathToArgumentList: filePath ];

                 // If we have reached the last attachment, it's time to hand control to the app:
                 if ( ++itemIdx >= m_inputItemCount )
                 {
                     [ self invokeApp: m_invokeArgs ];
                 }
             } ];
        }
    }
}
- ( void ) invokeApp: ( NSString * ) invokeArgs
{
    // Prepare the URL request
    // this will use the custom url scheme of your app
    // and the paths to the photos you want to share:
    NSString * urlString = [ NSString stringWithFormat: @"%@://%@", APP_SHARE_URL_SCHEME, ( NULL == invokeArgs ? @"" : invokeArgs ) ];
    NSURL * url = [ NSURL URLWithString: urlString ];

    NSString *className = @"UIApplication";
    if ( NSClassFromString( className ) )
    {
        id object = [ NSClassFromString( className ) performSelector: @selector( sharedApplication ) ];
        [ object performSelector: @selector( openURL: ) withObject: url ];
    }

    // Now let the host app know we are done, so that it unblocks its UI:
    [ super didSelectPost ];
}

#ifdef HIDE_POST_DIALOG
- ( NSArray * ) configurationItems
{
    // Comment out this whole function if you want the Post dialog to show.
    [ self passSelectedItemsToApp ];

    // To add configuration options via table cells at the bottom of the sheet, return an array of SLComposeSheetConfigurationItem here.
    return @[];
}
#endif


#ifdef HIDE_POST_DIALOG
- ( void ) willMoveToParentViewController: ( UIViewController * ) parent
{
    // This is called at the point where the Post dialog is about to be shown.
    // Make it transparent, so we don't see it, but first remember how transparent it was originally:

    m_oldAlpha = [ self.view alpha ];
    [ self.view setAlpha: 0.0 ];
}
#endif

#ifdef HIDE_POST_DIALOG
- ( void ) didMoveToParentViewController: ( UIViewController * ) parent
{
    // Restore the original transparency:
    [ self.view setAlpha: m_oldAlpha ];
}
#endif
#ifdef HIDE_POST_DIALOG
- ( id ) init
{
    if ( self = [ super init ] )
    {
        // Subscribe to the notification which will tell us when the keyboard is about to pop up:
        [ [ NSNotificationCenter defaultCenter ] addObserver: self selector: @selector( keyboardWillShow: ) name: UIKeyboardWillShowNotification    object: nil ];
    }

    return self;
}
#endif
#ifdef HIDE_POST_DIALOG
- ( void ) keyboardWillShow: ( NSNotification * ) note
{
    // Dismiss the keyboard before it has had a chance to show up:
    [ self.view endEditing: true ];
}
#endif
@end

2. In the openURL method of your application delegate

           //Slartibartfast -- For the case where we are opening app from an extension
            NSString *STATIC_FILE_HANDLE = @"file://";
           //If app is opened from share extension, do the following
           /*
            1.) Get path of shared file from NSUserDefaults
            2.) Get data from file and store in some variable
            3.) Create a new accesible unique file path
            4.) Dump data created into this file.
            */
   
           NSUserDefaults *defaults=[[NSUserDefaults alloc] initWithSuiteName:YOURAPP_STATIC_APP_GROUP_NAME];
           NSString *path=nil;
           if(defaults)
           {
               [defaults synchronize];
               path = [defaults stringForKey:@"url"];
           }
   
           if(path.length != 0)
           {
               NSData *data;
               //Get file path from url shared
               NSString * newFilePathConverted = [STATIC_FILE_HANDLE stringByAppendingString:path];
               url = [ NSURL URLWithString: newFilePathConverted ];
               data = [NSData dataWithContentsOfURL:url];
               //Create a regular access path because this app cant preview a shared app group path
               NSString *regularAccessPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
               NSString *uuid = [[NSUUID UUID] UUIDString];
               //Copy file to a jpg image(ignore extension, will convert from png)
               NSString *uniqueFilePath= [ NSString stringWithFormat: @"/image%@.jpg", uuid];
               regularAccessPath = [regularAccessPath stringByAppendingString:uniqueFilePath];
               NSString * newFilePathConverted1 = [STATIC_FILE_HANDLE stringByAppendingString:regularAccessPath];
               url = [ NSURL URLWithString: newFilePathConverted1 ];
               //Dump existing shared file path data into newly created file.
               [data writeToURL:url atomically:YES];
               //Reset NSUserDefaults to Nil once file is copied.
               [defaults setObject:nil forKey:@"url"];
   
           }
       //Do what you want
       }
   

Thanks to EasyNativeExtensions for pointers