FolderFinder.m

// Credit: u/Mordred666
// Source: https://reddit.com/r/jailbreakdevelopers/comments/5wb3tv/application_appgroup_path/

#import "FolderFinder.h"

@implementation FolderFinder : NSObject
  +(NSString*) findSharedFolder:(NSString*) appName {
    NSString *dir = @"/var/mobile/Containers/Shared/AppGroup/";
    NSString* result = [self findFolder:appName folder:dir];
    return result;
  }

  +(NSString*) findFolder:(NSString*) appName folder:(NSString*) dir {
    NSFileManager *manager = [NSFileManager defaultManager];

    NSError *error = nil;
    NSArray *folders = [manager contentsOfDirectoryAtPath:dir error:&error];

    if (!error) {
      for (NSString *folder in folders) {
        NSString *folderPath = [dir stringByAppendingString:folder];
        NSArray *items = [manager contentsOfDirectoryAtPath:folderPath error:&error];

        for(NSString* itemPath in items) {
          if([itemPath rangeOfString:@".com.apple.mobile_container_manager.metadata.plist"].location != NSNotFound) {
            NSString* fullpath = [NSString stringWithFormat:@"%@/%@",folderPath, itemPath];
            NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:fullpath];

            NSString* mcmmetadata = dict[@"MCMMetadataIdentifier"];
            if(mcmmetadata && [mcmmetadata.lowercaseString isEqualToString:appName.lowercaseString]) {
              return folderPath;
            }
          }
        }

      }
    }
    return nil;
  }
@end